SEC Form POS AM filed by Perspective Therapeutics Inc.

As filed with the Securities and Exchange Commission on March 26, 2025

Registration No. 333-279692

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

POST-EFFECTIVE AMENDMENT NO. 2

TO

FORM S-3

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933

Perspective Therapeutics, Inc.

(Exact name of registrant as specified in its charter)

2401 Elliott Avenue, Suite 320

Seattle, WA 98121

(206) 676-0900

(Address, including zip code, and telephone number, including area code, of registrant’s principal executive offices)

Johan (Thijs) Spoor

Chief Executive Officer

Perspective Therapeutics, Inc.

2401 Elliott Avenue, Suite 320

Seattle, WA 98121

(206) 676-0900

(Name, address, including zip code, and telephone number, including area code, of agent for service)

Copies to:

Approximate date of commencement of proposed sale to the public: From time to time after the effective date of this Registration Statement.

If the only securities being registered on this Form are being offered pursuant to dividend or interest reinvestment plans, please check the following box. ☐

If any of the securities being registered on this Form are to be offered on a delayed or continuous basis pursuant to Rule 415 under the Securities Act of 1933, other than securities offered only in connection with dividend or interest reinvestment plans, check the following box. ☒

If this Form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, please check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. ☐

If this Form is a post-effective amendment filed pursuant to Rule 462(c) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. ☐

If this Form is a registration statement pursuant to General Instruction I.D. or a post-effective amendment thereto that shall become effective upon filing with the Commission pursuant to Rule 462(e) under the Securities Act, check the following box. ☐

If this Form is a post-effective amendment to a registration statement filed pursuant to General Instruction I.D. filed to register additional securities or additional classes of securities pursuant to Rule 413(b) under the Securities Act, check the following box. ☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 7(a)(2)(B) of the Securities Act. ☐

The Registrant hereby amends this Registration Statement on such date or dates as may be necessary to delay its effective date until the Registrant shall file a further amendment which specifically states that this Registration Statement shall thereafter become effective in accordance with Section 8 (a) of the Securities Act of 1933 or until the Registration Statement shall become effective on such date as the Commission acting pursuant to said Section 8 (a) may determine.

EXPLANATORY NOTE

Post-Effective Amendment No. 1 to the Registration Statement on Form S-3 (File No. 333-279692) filed with the Securities and Exchange Commission on May 24, 2024 (as so amended, the Registration Statement) of Perspective Therapeutics, Inc., or the Registrant, was filed on March 26, 2025 because the Registrant expected that it would no longer be a well-known seasoned issuer, as such term is defined in Rule 405 under the Securities Act of 1933, as amended, when it filed its Annual Report on Form 10-K for the year ended December 31, 2024 because the worldwide market value of its outstanding common stock held by non-affiliates would be less than $700 million during the 60-day period preceding the date of such filing. Pursuant to interpretive guidance published by the Securities and Exchange Commission’s Division of Corporation Finance, Post-Effective Amendment No. 1 was filed to add disclosure to the Registration Statement required for a registrant other than a well-known seasoned issuer and made certain other amendments. This Post-Effective Amendment No. 2 is being filed using EDGAR submission type POS AM to convert the Registration Statement to the proper EDGAR submission type for a non-automatic shelf registration and to make certain other amendments.

This Post-Effective Amendment No. 2 to the Registration Statement contains:

The base prospectus immediately follows this explanatory note. The specific terms of any securities to be offered pursuant to the base prospectus, other than the shares under the Sales Agreement, will be specified in one or more prospectus supplements to the base prospectus.

The specific terms of the securities to be issued and sold under the Sales Agreement are specified in the sales agreement prospectus that immediately follows the base prospectus. The $250.0 million of common stock that may be offered, issued and sold under the sales agreement prospectus is included in the $500.0 million of securities that may be offered, issued and sold by us under the base prospectus. Upon any termination of the offering under the Sales Agreement, any portion of the $250.0 million of securities included in the sales agreement prospectus that has not been sold pursuant to the Sales Agreement will become available for sale in other offerings pursuant to the base prospectus with a corresponding prospectus supplement. As of March 24, 2025, the Registrant has sold $10,205,718.54 of the common stock under the sales agreement prospectus supplement pursuant to the Registration Statement.

The information contained in this prospectus is not complete and may be changed. These securities may not be sold until the registration statement filed with the Securities and Exchange Commission is effective. This prospectus is not an offer to sell these securities and it is not soliciting an offer to buy these securities in any jurisdiction where such offer or sale is not permitted.

SUBJECT TO COMPLETION, DATED MARCH 26, 2025

PROSPECTUS

$500,000,000

Common Stock

Preferred Stock

Warrants

Debt Securities

Units

We may offer to the public from time to time in one or more series or issuances and on terms that we will determine at the time of the offering:

The aggregate initial offering price of all securities sold by us pursuant to this prospectus will not exceed $500,000,000.

This prospectus provides a general description of the securities that we may offer. Each time that we offer securities under this prospectus, we will provide the specific terms of the securities offered, including the public offering price, in a supplement to this prospectus. Any prospectus supplement may add to, update or change information contained or incorporated by reference in this prospectus.

The securities may be sold by us to or through underwriters or dealers, directly to purchasers or through agents designated from time to time. For additional information on the methods of sale, you should refer to the section entitled “Plan of Distribution” in this prospectus and the comparable section of any applicable prospectus supplement. If any underwriters are involved in the sale of the securities with respect to which this prospectus is being delivered, the names of such underwriters and any applicable discounts, commissions and purchase options will be set forth in the applicable prospectus supplement.

Our common stock trades on the NYSE American under the ticker symbol “CATX.” On March 24, 2025, the last reported sale price per share of our common stock was $2.52. We have not yet determined whether the other

securities that may be offered by this prospectus will be listed on any exchange, interdealer quotation system or over-the-counter market. If we decide to seek the listing of any such securities upon issuance, the prospectus supplement relating to those securities will disclose the exchange, quotation system or market on which those securities will be listed.

INVESTING IN OUR SECURITIES INVOLVES A HIGH DEGREE OF RISK. RISKS ASSOCIATED WITH AN INVESTMENT IN OUR SECURITIES WILL BE DESCRIBED IN THE APPLICABLE PROSPECTUS SUPPLEMENT AND CERTAIN OF OUR FILINGS WITH THE SECURITIES AND EXCHANGE COMMISSION INCORPORATED BY REFERENCE INTO THIS PROSPECTUS, AS DESCRIBED UNDER “RISK FACTORS” ON PAGE 4.

You should read this prospectus and any applicable prospectus supplement together with additional information described under the heading “Where You Can Find More Information” before you make your investment decision.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined if this prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

The date of this prospectus is , 2025

TABLE OF CONTENTS

ABOUT THIS PROSPECTUS

This prospectus is a part of a registration statement on Form S-3 that we filed with the Securities and Exchange Commission, or the SEC, using a “shelf” registration process. Under this shelf registration process, we may offer to sell any of the securities, or any combination of the securities, described in this prospectus, in each case in one or more offerings up to a total dollar amount of $500,000,000.

This prospectus provides you only with a general description of the securities that we may offer. Each time securities are sold under this shelf registration statement, we will provide an accompanying prospectus supplement that will contain specific information about the terms of those securities and the terms of that offering. The accompanying prospectus supplement may also add, update or change information contained in this prospectus. If there is any inconsistency between the information in this prospectus and any accompanying prospectus supplement, you should rely on the information in the accompanying prospectus supplement. You should read both this prospectus and any accompanying prospectus supplement, including all documents incorporated by reference herein and therein, together with the additional information described under “Where You Can Find More Information” below.

The information contained in this prospectus is not complete and may be changed. We have not authorized any dealer, agent or other person to give any information or to make any representation other than those contained or incorporated by reference in this prospectus and any accompanying prospectus supplement. We take no responsibility for, and can provide no assurance as to the reliability of, any other information that others may give you. We will not make an offer to sell or solicit an offer to buy these securities in any jurisdiction where the offer or sale is not permitted. This prospectus and the accompanying prospectus supplement, if any, do not constitute an offer to sell or the solicitation of an offer to buy any securities other than the registered securities to which they relate, nor do this prospectus and the accompanying prospectus supplement, if any, constitute an offer to sell or the solicitation of an offer to buy securities in any jurisdiction to any person to whom it is unlawful to make such offer or solicitation in such jurisdiction. You should not assume that the information contained in this prospectus and the accompanying prospectus supplement, if any, is accurate on any date subsequent to the date set forth on the front of such document or that any information we have incorporated by reference is correct on any date subsequent to the date of the document incorporated by reference, even though this prospectus and any accompanying prospectus supplement is delivered or securities are sold on a later date.

This prospectus and the documents incorporated by reference herein and therein contain estimates, projections, market research and other information concerning, among other things, our industry, our business, and markets for our program candidates. Unless otherwise expressly stated, we obtain this information from reports, research surveys, studies and similar data prepared by market research firms and other third parties, industry, medical and general publications, government data and similar sources as well as from our own internal estimates and research and from publications, research, surveys and studies conducted by third parties on our behalf. We believe this information is accurate in all material respects as of the date of this prospectus. Information that is based on estimates, projections, market research or similar methodologies is inherently subject to uncertainties and actual events or circumstances may differ materially from events and circumstances that are reflected in this information.

Unless the context requires otherwise, in this prospectus the terms “Perspective Therapeutics,” “the Company,” “we,” “us,” “our,” and similar terms refer to Perspective Therapeutics, Inc. and its subsidiaries. Unless otherwise stated or indicated by context, the phrase “this prospectus” refers to the prospectus and any applicable prospectus supplement.

“Perspective Therapeutics” and the Perspective Therapeutics logo are our trademarks. This prospectus and the documents incorporated by reference into this prospectus may also contain trademarks and trade names that are the property of their respective owners. We do not intend our use or display of other companies’ trade names, trademarks or service marks to imply relationships with, or endorsements or sponsorship of us by, these other companies.

FORWARD-LOOKING STATEMENTS

This prospectus and the documents incorporated by reference herein contain, and any prospectus supplement and the documents incorporated therein, may contain, forward-looking statements that involve substantial risks and uncertainties. All statements, other than statements of historical facts, included in this prospectus, any prospectus supplement or the documents incorporated herein and therein by reference, including statements regarding our future financial condition, results of operations, business strategy and plans and objectives of management for future operations, industry trends and other future events, are forward-looking statements. In some cases, you can identify forward-looking statements by terminology such as “may,” “anticipate,” “believe,” “could,” “expect,” “intend,” “might,” “plan,” “possible,” “potential,” “aim,” “predict,” “project,” “should,” “will,” “would” or the negative of these terms or other similar expressions, although not all forward-looking statements contain these identifying terms. The forward-looking statements in this prospectus and the documents incorporated herein by reference include, among other things, statements about:

We may not actually achieve the plans, intentions or expectations disclosed in the forward-looking statements and you should not place undue reliance on the forward-looking statements. These forward-looking statements involve risks and uncertainties that could cause our actual results to differ materially from the results described in or implied by the forward-looking statements, including without limitation, the potential that regulatory authorities may not grant or may delay approval for our program candidates; uncertainties and delays relating to the design, enrollment, completion and results of clinical trials; unanticipated costs and expenses; early clinical trials may not be indicative of the results in later clinical trials; clinical trial results may not support regulatory approval or further development in a specified indication or at all; actions or advice of regulatory authorities may affect the design, initiation, timing, continuation and/or progress of clinical trials or result in the need for additional clinical trials; our ability to obtain and maintain regulatory approval for our program candidates; delays, interruptions or failures in the manufacture and supply of our program candidates; the size and growth potential of the markets for our program candidates, and our ability to service those markets; our cash and cash equivalents may not be sufficient to support our operating plan for as long as anticipated; our expectations, projections and estimates regarding expenses, future revenue, capital requirements, and the availability of and the need for additional financing; our ability to obtain additional funding to support our clinical development programs; the availability or potential availability of alternative products or treatments for conditions

targeted by us that could affect the availability or commercial potential of our program candidates; our ability to manage growth and successfully integrate our businesses; whether we can retain our key employees; whether there is sufficient training and use of our programs and program candidates; the market acceptance and recognition of our programs and program candidates; our ability to maintain and enforce our intellectual property rights; whether we can maintain our therapeutic isotope supply agreement with the Department of Energy; whether we will continue to comply with the procedures and regulatory requirements mandated by the Food and Drug Administration for additional trials, Phase 1 and 2 approvals, Fast Track approvals, and 510(k) approval and reimbursement codes; and any changes in applicable laws and regulations. Other factors that may cause our actual results to differ materially from those expressed or implied in the forward-looking statements are described under the heading “Risk Factors” in our most recent Annual Report on Form 10-K and Quarterly Reports on Form 10-Q, each filed with the SEC, in our other filings with the SEC, and in our future reports to be filed with the SEC and available at www.sec.gov.

Should known or unknown risks materialize, or should underlying assumptions prove inaccurate, actual results could differ materially from past results and those anticipated, estimated or projected in the forward-looking statements. You should bear this in mind as you consider any forward-looking statements.

You should read this prospectus, any prospectus supplement and the documents that we incorporate by reference herein and therein completely and with the understanding that our actual future results may be materially different from what we expect. The forward-looking statements contained in this prospectus are made as of the date of this prospectus, and we undertake no duty to update such forward-looking statements, whether as a result of new information, future events or otherwise, except as required by applicable law.

SUMMARY

This summary highlights selected information from this prospectus and does not contain all of the information that you need to consider in making your investment decision. You should carefully read the entire prospectus, the applicable prospectus supplement and any related free writing prospectus, including the risks of investing in our securities discussed under the heading “Risk Factors” contained in the applicable prospectus supplement and any related free writing prospectus, and under similar headings in the other documents that are incorporated by reference into this prospectus. You should also carefully read the information incorporated by reference into this prospectus, including our financial statements, and the exhibits to the registration statement of which this prospectus is a part.

Company Overview

We are a radiopharmaceutical development company that is pioneering advanced treatment applications for cancers throughout the body. We have proprietary technology that utilizes the alpha-emitting isotope Lead-212 (212Pb) to deliver powerful radiation specifically to cancer cells via specialized targeting moieties. We are also developing complementary imaging diagnostics that incorporate the same targeting moieties which provide the opportunity to personalize treatment and optimize patient outcomes. This theranostic approach enables the ability to see the specific tumor and then treat it to potentially improve efficacy and minimize toxicity.

Our melanoma (VMT01) and neuroendocrine tumor (VMT-α-NET) programs are in Phase 1/2a imaging and therapy trials for the treatment of metastatic melanoma and neuroendocrine tumors in the U.S. We are growing our regional network of drug product finishing facilities, enabled by our proprietary 212Pb generator, to deliver patient-ready products for clinical trial and commercial operations.

For more information about our company, please refer to other documents that we have filed with the SEC and that are incorporated by reference in this prospectus supplement, as listed in the section entitled “Incorporation of Certain Information by Reference.”

Corporate Information

Our predecessor company, Isoray, Inc. was incorporated in 1983 in Minnesota and operated under the name Century Park Pictures Corporation until the merger with Isoray Medical, Inc. on July 28, 2005. Isoray, Inc. reincorporated from Minnesota to Delaware in December 2018. On February 14, 2023, we changed our corporate name to Perspective Therapeutics, Inc.

Our principal executive offices are located at 2401 Elliott Avenue, Suite 320, Seattle, Washington 98121, and our telephone number is (206) 676-0900. We maintain a website at www.perspectivetherapeutics.com. The inclusion of our website address is intended to be an inactive textual reference only and not an active hyperlink to our website. The information contained in, or that can be accessed through, our website address is not incorporated by reference into this prospectus and is not part of this prospectus. The SEC also maintains an internet website located at www.sec.gov that contains the information we file or furnish electronically with the SEC.

RISK FACTORS

Investing in our securities involves a high degree of risk. The prospectus supplement applicable to each offering of our securities will contain a discussion of the risks applicable to an investment in our securities. Prior to making a decision about investing in our securities, you should carefully consider the specific factors discussed under the heading “Risk Factors” in the applicable prospectus supplement, together with all of the other information contained or incorporated by reference in the prospectus supplement or appearing or incorporated by reference in this prospectus. You should also consider the risks, uncertainties and assumptions discussed under the heading “Risk Factors” in our most recent Annual Report on Form 10-K and our Quarterly Reports on Form 10-Q and other documents that we file with the SEC, which are incorporated herein by reference as described in this prospectus under the heading “Where You Can Find More Information.” The risks and uncertainties we have described in such documents are not the only risks that we face. Additional risks and uncertainties not presently known to us or that we currently deem immaterial may also affect our operations.

USE OF PROCEEDS

Except as otherwise provided in the applicable prospectus supplement relating to a specific offering, we intend to use the net proceeds from the sale of securities by us under this prospectus and any applicable prospectus supplement for general corporate purposes, which may include research and development expenditures, preclinical study and clinical trial expenditures, manufacturing expenditures, commercialization expenditures, working capital, capital expenditures, acquisitions of new technologies, products or businesses, and investments. We may also use a portion of the net proceeds from this offering to acquire or invest in complementary businesses, technologies, product candidates or other intellectual property, although we have no present commitments or agreements to do so. Additional information on the use of net proceeds from the sale of securities by us under this prospectus may be set forth in the accompanying prospectus supplement relating to the specific offering.

PLAN OF DISTRIBUTION

We may sell the securities, from time to time pursuant to public offerings, negotiated transactions, block trades, “At the Market Offerings,” within the meaning of Rule 415(a)(4) of the Securities Act of 1933, as amended, or the Securities Act, into an existing trading market, at prevailing market prices, or a combination of these methods. We may sell the securities to or through underwriters or dealers, through agents or remarketing firms, or directly to one or more purchasers. We may distribute securities from time to time in one or more transactions:

A prospectus supplement or supplements (and any related free writing prospectus that we may authorize to be provided to you) will describe the terms of the offering of the securities, including, to the extent applicable:

Only underwriters named in the prospectus supplement will be underwriters of the securities offered by the prospectus supplement.

If underwriters are used in the sale, they will acquire the securities for their own account and may resell the securities from time to time in one or more transactions at a fixed public offering price or at varying prices determined at the time of sale. The obligations of the underwriters to purchase the securities will be subject to the conditions set forth in the applicable underwriting agreement. We may offer the securities to the public through underwriting syndicates represented by managing underwriters or by underwriters without a syndicate. Unless otherwise indicated in the prospectus supplement, subject to certain conditions, the underwriters will be obligated to purchase all of the securities offered by the prospectus supplement, other than securities covered by any purchase option. Any public offering price and any discounts or concessions allowed or reallowed or paid to dealers may change from time to time. We may use underwriters, dealers or agents with whom we have a material relationship. We will describe in the prospectus supplement, naming the underwriter, dealer or agent, the nature of any such relationship.

We may use a remarketing firm to offer the securities in connection with a remarketing arrangement upon their purchase. Remarketing firms will act as principals for their own account or as agents for us. These remarketing firms will offer or sell the securities pursuant to the terms of the securities. A prospectus supplement will identify any remarketing firm and the terms of its agreement, if any, with us and will describe the remarketing firm’s compensation. Remarketing firms may be deemed to be underwriters in connection with the securities they remarket.

If we offer and sell securities through a dealer, we or an underwriter will sell the securities to the dealer, as principal. The dealer may then resell the securities to the public at varying prices to be determined by the dealer at the time of resale. The name of the dealer and the terms of the transaction will be set forth in the applicable prospectus supplement.

We may sell securities directly or through agents we designate from time to time. We will name any agent involved in the offering and sale of securities and we will describe any commissions we will pay to the agent in the prospectus supplement. Unless the prospectus supplement states otherwise, our agent will act on a best-efforts basis for the period of its appointment.

Dealers and agents participating in the distribution of the securities may be deemed to be underwriters, and compensation received by them on resale of the securities may be deemed to be underwriting discounts. If such dealers or agents were deemed to be underwriters, they may be subject to statutory liabilities under the Securities Act.

We may sell securities directly to one or more purchasers without using underwriters or agents. Underwriters, dealers and agents that participate in the distribution of the securities may be underwriters as defined in the Securities Act, and any discounts or commissions they receive from us and any profit on their resale of the securities may be treated as underwriting discounts and commissions under the Securities Act.

We may authorize agents or underwriters to solicit offers by certain types of institutional investors to purchase securities from us at the public offering price set forth in the prospectus supplement pursuant to delayed delivery contracts providing for payment and delivery on a specified date in the future. We will describe the conditions to these contracts and the commissions we must pay for solicitation of these contracts in the prospectus supplement.

We may provide agents, underwriters and dealers with indemnification against civil liabilities, including liabilities under the Securities Act, or contribution with respect to payments that the agents, underwriters or dealers may make with respect to these liabilities. Agents, underwriters and dealers, or their respective affiliates, may engage in transactions with, or perform services for, us in the ordinary course of business.

All securities we may offer, other than common stock, will be new issues of securities with no established trading market. Any underwriter may make a market in these securities, but will not be obligated to do so and may discontinue any market making at any time without notice. We cannot guarantee the liquidity of the trading markets for any securities.

Any underwriter may engage in purchase options, stabilizing transactions, short-covering transactions and penalty bids in accordance with Regulation M under the Securities Exchange Act of 1934, as amended, or the Exchange Act. Purchase options involve sales in excess of the offering size, which create a short position. Stabilizing transactions permit bids to purchase the underlying security so long as the stabilizing bids do not exceed a specified maximum price. Syndicate-covering or other short-covering transactions involve purchases of the securities, either through exercise of the purchase option or in the open market after the distribution is completed, to cover short positions. Penalty bids permit the underwriters to reclaim a selling concession from a dealer when the securities originally sold by the dealer are purchased in a stabilizing or covering transaction to cover short positions. Those activities may cause the price of the securities to be higher than it would otherwise be. If commenced, the underwriters may discontinue any of the activities at any time.

Any underwriters that are qualified market makers on the New York Stock Exchange may engage in passive market making transactions in our common stock on the New York Stock Exchange in accordance with Regulation M under the Exchange Act, during the business day prior to the pricing of the offering, before the commencement of offers or sales of our common stock. Passive market makers must comply with applicable volume and price limitations and must be identified as passive market makers. In general, a passive market maker must display its bid at a price not in excess of the highest independent bid for such security; if all independent bids are lowered below the passive market maker’s bid, however, the passive market maker’s bid must then be lowered when certain purchase limits are exceeded. Passive market making may stabilize the market price of the securities at a level above that which might otherwise prevail in the open market and, if commenced, may be discontinued at any time.

GENERAL DESCRIPTION OF OUR SECURITIES

We may offer and sell, at any time and from time to time:

The terms of any securities we offer will be determined at the time of sale. We may issue debt securities that are exchangeable for and/or convertible into common stock or any of the other securities that may be sold under this prospectus. When particular securities are offered by us, a supplement to this prospectus will be filed with the SEC, which will describe the terms of the offering and sale of the offered securities.

DESCRIPTION OF OUR COMMON STOCK

The summary of general terms and provisions of our common stock set forth below does not purport to be complete and is subject to and qualified by reference to our Amended and Restated Certificate of Incorporation (the “Certificate of Incorporation”) and Amended and Restated Bylaws (the “Bylaws,” and together with the Certificate of Incorporation, the “Charter Documents”), each of which is included as an exhibit to our most recent Annual Report on Form 10-K filed with the SEC and incorporated by reference herein. For additional information, please read the Charter Documents and the applicable provisions of the Delaware General Corporation Law (the “DGCL”).

General

We are authorized to issue up to 750,000,000 shares of common stock, par value $0.001 per share.

The holders of our common stock have no preemptive or other subscription rights, and there are no conversion rights or redemption or sinking fund provisions with respect to such shares of common stock. All of the outstanding shares of our common stock are, and the shares of our common stock when issued will be, fully paid and nonassessable.

Voting. Holders of our common stock are entitled to one vote per share of common stock on all matters to be voted on by our stockholders, provided, however, that, except as otherwise required by law, holders of common stock are not entitled to vote on any amendment to the Certificate of Incorporation that relates solely to the terms of one or more outstanding series of preferred stock if the holders of such affected series are entitled, either separately or together as a class with the holders of one or more other such series, to vote thereon pursuant to the Certificate of Incorporation. The Bylaws provide that except as otherwise provided by applicable law, the Certificate of Incorporation, or the Bylaws, the presence, in person or by proxy, of the holders of a majority of the voting power of all outstanding shares of stock entitled to vote at the meeting constitutes a quorum.

Dividends. Our Board of Directors (our “Board”), in its sole discretion, may declare and pay dividends on our common stock, payable in cash or other consideration, out of funds legally available, if all dividends due on the preferred stock have been declared and paid. We have not paid any cash dividends on our common stock and do not plan to pay any cash dividends on our common stock for the foreseeable future.

Liquidation, Subdivision, or Combination. In the event of any liquidation, dissolution or winding up of us or upon the distribution of our assets, all assets and funds remaining after payment in full of our debts and liabilities, and after the payment to holders of any then outstanding preferred stock of the full preferential amounts to which they were entitled, would be divided and distributed among holders of the common stock.

Anti-Takeover Provisions

Section 203 of the Delaware General Corporation Law

Pursuant to the Certificate of Incorporation, we elected not to be governed by Section 203 of the DGCL, which prohibits a Delaware corporation from engaging in any business combination with any interested stockholder for a period of three years after the date that such stockholder became an interested stockholder, with certain exceptions.

Amended and Restated Certificate of Incorporation and Amended and Restated Bylaws

Because our stockholders do not have cumulative voting rights, stockholders holding a majority of the shares of common stock outstanding are able to elect all of our directors. The Bylaws provide that directors may be removed by the stockholders with or without cause upon the vote of a majority of the shares then entitled to vote at an election of directors. Furthermore, the authorized number of directors may be changed only by resolution of our Board, and vacancies and newly created directorships on our Board may, except as otherwise required by law or the Certificate of Incorporation, only be filled by a majority vote of the directors then serving on our Board, even though less than a quorum.

The Bylaws also provide that stockholders seeking to present proposals before a meeting of stockholders to nominate candidates for election as directors or any other business to be properly brought at a meeting of stockholders must provide timely advance notice in writing and specify requirements as to the form and content of a stockholder’s notice.

The Certificate of Incorporation provides our Board the authority, without further action by our stockholders, to issue up to 7,000,000 shares of preferred stock in one or more series, with any rights, preferences and privileges as they may designate, including the right to approve an acquisition or other change in control.

The combination of these provisions makes it more difficult for our existing stockholders to replace our Board as well as for another party to obtain control of us by replacing our Board. Since our Board has the power to retain and discharge our officers, these provisions could also make it more difficult for existing stockholders or another party to effect a change in management. In addition, the authorization of undesignated preferred stock makes it possible for our Board to issue preferred stock with voting or other rights or preferences that could impede the success of any attempt to change control of us.

These provisions are intended to enhance the likelihood of continued stability in the composition of our Board and its policies and to discourage coercive takeover practices and inadequate takeover bids. These provisions are also designed to reduce our vulnerability to hostile takeovers and to discourage certain tactics that may be used in proxy fights. However, such provisions could have the effect of discouraging others from making tender offers for our shares and may have the effect of delaying changes in our control or management. As a consequence, these provisions may also inhibit fluctuations in the market price of our stock that could result from actual or rumored takeover attempts. We believe that the benefits of these provisions, including increased protection of our potential ability to negotiate with the proponent of an unfriendly or unsolicited proposal to acquire or restructure our company, outweigh the disadvantages of discouraging takeover proposals, because negotiation of takeover proposals could result in an improvement of their terms.

Choice of Forum

Our Bylaws provide that, unless we consent in writing to the selection of an alternative forum, the sole and exclusive forum for any claim or counterclaim, including without limitation (i) any derivative action or proceeding brought on behalf of the us, (ii) any action asserting a claim of breach of a fiduciary duty owed by any of our directors, officers or other employees to us or our stockholders, (iii) any action asserting a claim arising pursuant to any provision of the DGCL, or (iv) any action asserting a claim governed by the internal affairs doctrine, shall be a state or federal court located within the State of Delaware, in all cases subject to the court having personal jurisdiction over the indispensable parties named as defendants. While the Delaware courts have determined that such choice of forum provisions are facially valid, a stockholder may nevertheless seek to bring a claim in a venue other than those designated in the exclusive forum provisions. In such instance, we would expect to vigorously assert the validity and enforceability of the exclusive forum provisions of our Bylaws. This may require significant additional costs associated with resolving such action in other jurisdictions and there can be no assurance that the provisions will be enforced by a court in those other jurisdictions

These exclusive forum provisions may result in increased costs for investors to bring a claim. Further, these exclusive forum provisions may limit a stockholder’s ability to bring a claim in a judicial forum that it finds favorable for disputes with us or our directors, officers, or other employees, which may discourage lawsuits against us and our directors, officers and other employees. If a court were to find the exclusive-forum provision in our Bylaws to be inapplicable or unenforceable in an action, we may incur further significant additional costs associated with resolving the dispute in other jurisdictions, all of which could seriously harm our business.

Transfer Agent and Registrar

The transfer agent and registrar for our common stock is Computershare Trust Company, N.A . The transfer agent’s address is 150 Royall St., Suite 101, Canton, Massachusetts 02021, and its telephone number is (800) 962-4284.

Listing

Our common stock is listed on the NYSE American under the trading symbol “CATX.”

DESCRIPTION OF OUR PREFERRED STOCK

The summary of general terms and provisions of our preferred stock set forth below does not purport to be complete and is subject to and qualified by reference to the Certificate of Incorporation and the Bylaws, each of which is included as an exhibit to our most recent Annual Report on Form 10-K filed with the SEC and incorporated by reference herein. For additional information, please read the Charter Documents and the applicable provisions of the DGCL.

We are authorized to issue up to 7,000,000 shares of preferred stock, par value $0.001 per share.

Our Board may, without further action by our stockholders, from time to time, direct the issuance of shares of preferred stock in series and may, at the time of issuance, determine and fix the number of shares of such series of preferred stock and the designation of such series of preferred stock, the voting powers, if any, of the shares of such series of preferred stock, the preferences and relative, participating, optional or other special rights, if any, and the qualifications, limitations or restrictions thereof, including without limitation thereof, dividend rights, conversion rights, redemption privileges and liquidation preferences, of the shares of such series of preferred stock. Satisfaction of any dividend preferences of outstanding shares of our preferred stock would reduce the amount of funds available for the payment of dividends on shares of our common stock. Holders of shares of our preferred stock may be entitled to receive a preference payment in the event of any liquidation, dissolution or winding-up of our company before any payment is made to the holders of shares of our common stock. In some circumstances, the issuance of shares of preferred stock may render more difficult or tend to discourage a merger, tender offer or proxy contest, the assumption of control by a holder of a large block of our securities or the removal of incumbent management. Upon the affirmative vote of our Board, without stockholder approval, we may issue shares of preferred stock with voting and conversion rights which could adversely affect the holders of shares of our common stock. It is not possible to state the actual effect of the issuance of any shares of our preferred stock on the rights of holders of our common stock until the Board determines the specific rights attached to that preferred stock.

If we offer a specific series of preferred stock under this prospectus, we will describe the terms of the preferred stock in the prospectus supplement for such offering and will file a copy of the certificate establishing the terms of the preferred stock with the SEC. To the extent required, this description will include:

The preferred stock offered by this prospectus, when issued, will not have, or be subject to, any preemptive or similar rights.

Series B Convertible Preferred Stock

Of the 7,000,000 shares of presently authorized preferred stock, 5,000,000 are designated as Series B convertible preferred stock. As of March 24, 2025, no shares of our Series B convertible preferred stock were issued and outstanding.

Each share of Series B convertible preferred stock is entitled to a cumulative 15% dividend annually on the stated par value per share, which is $1.20 per share. These shares of Series B convertible preferred stock are convertible into shares of our common stock at the rate of one share of common stock for each share of Series B convertible preferred stock, and are subject to automatic conversion into our common stock upon the closing of a firmly underwritten public offering pursuant to an effective registration statement under the Securities Act covering the offer and sale of our common stock in which the gross proceeds to us are at least $4.0 million. Holders of Series B convertible preferred stock have voting rights equal to the voting rights of our common stock, except that the vote or written consent of a majority of the outstanding shares our Series B convertible preferred stock is required for any changes to the Certificate of Incorporation, Bylaws, or Certificate of Designation, or for any bankruptcy, insolvency, dissolution, or liquidation of us. Upon liquidation of our company, our assets will be distributed ratably first to the holders of the Series B convertible preferred stock and second to the holders of our common stock.

Transfer Agent and Registrar

The transfer agent and registrar for any series of preferred stock will be set forth in each applicable prospectus supplement.

DESCRIPTION OF OUR WARRANTS

We may issue warrants to purchase shares of our common stock, preferred stock and/or debt securities in one or more series together with other securities or separately, as described in each applicable prospectus supplement. Below is a description of certain general terms and provisions of the warrants that we may offer. Particular terms of the warrants will be described in the applicable warrant agreements and the applicable prospectus supplement for the warrants.

The applicable prospectus supplement will contain, where applicable, the following terms of and other information relating to the warrants:

Transfer Agent and Registrar

The transfer agent and registrar for any warrants will be set forth in the applicable prospectus supplement.

DESCRIPTION OF OUR DEBT SECURITIES

This section describes the general terms and provisions of the debt securities that we may offer under this prospectus, any of which may be issued as convertible or exchangeable debt securities. We will set forth the particular terms of the debt securities we offer in a prospectus supplement. The extent, if any, to which the following general provisions apply to particular debt securities will be described in the applicable prospectus supplement. The following description of general terms relating to the debt securities and the indenture under which the debt securities will be issued are summaries only and therefore are not complete. You should read the indenture and the prospectus supplement regarding any particular issuance of debt securities.

We will issue the debt securities offered by this prospectus and any accompanying prospectus supplement under an indenture to be entered into between us and the trustee identified in the applicable prospectus supplement. The terms of the debt securities will include those stated in the indenture and those made part of the indenture by reference to the Trust Indenture Act of 1939, as in effect on the date of the indenture. We have filed or will file a copy of the form of indenture as an exhibit to the registration statement in which this prospectus is included. The indenture will be subject to and governed by the terms of the Trust Indenture Act of 1939.

We may offer under this prospectus up to an aggregate principal amount of $500,000,000 in debt securities, or if debt securities are issued at a discount, or in a foreign currency, foreign currency units or composite currency, the principal amount as may be sold for an aggregate initial public offering price of up to $500,000,000.

Unless otherwise specified in the applicable prospectus supplement, the debt securities will represent direct, unsecured obligations of ours and will rank equally with all of our other unsecured indebtedness.

The following statements relating to the debt securities and the indenture are summaries, qualified in their entirety by reference to the detailed provisions of the indenture and the final form indenture as may be filed with a future prospectus supplement.

General

We may issue the debt securities in one or more series with the same or various maturities, at par, at a premium, or at a discount. We will describe the particular terms of each series of debt securities in a prospectus supplement relating to that series, which we will file with the SEC.

The prospectus supplement will set forth, to the extent required, the following terms of the debt securities in respect of which the prospectus supplement is delivered:

We may issue discount debt securities that provide for an amount less than the stated principal amount to be due and payable upon acceleration of the maturity of such debt securities in accordance with the terms of the indenture. We may also issue debt securities in bearer form, with or without coupons. If we issue discount debt securities or debt securities in bearer form, we will describe material U.S. federal income tax considerations and other material special considerations that apply to these debt securities in the applicable prospectus supplement.

We may issue debt securities denominated in or payable in a foreign currency or currencies or a foreign currency unit or units. If we do, we will describe the restrictions, elections, and general tax considerations relating to the debt securities and the foreign currency or currencies or foreign currency unit or units in the applicable prospectus supplement.

Exchange and/or Conversion Rights

We may issue debt securities which can be exchanged for or converted into shares of our common stock or preferred stock. If we do, we will describe the terms of exchange or conversion in the prospectus supplement relating to these debt securities.

Transfer and Exchange

We may issue debt securities that will be represented by either:

We will specify in the prospectus supplement applicable to a particular offering whether the debt securities offered will be book-entry or certificated securities.

Certificated Debt Securities

If you hold certificated debt securities issued under an indenture, you may transfer or exchange such debt securities in accordance with the terms of the indenture. You will not be charged a service charge for any transfer or exchange of certificated debt securities but may be required to pay an amount sufficient to cover any tax or other governmental charge payable in connection with such transfer or exchange.

Global Securities

The debt securities of a series may be issued in the form of one or more global securities that will be deposited with a depositary or its nominees identified in the prospectus supplement relating to the debt securities. In such a case, one or more global securities will be issued in a denomination or aggregate denominations equal to the portion of the aggregate principal amount of outstanding debt securities of the series to be represented by such global security or securities.

Unless and until it is exchanged in whole or in part for debt securities in definitive registered form, a global security may not be registered for transfer or exchange except as a whole by the depositary for such global security to a nominee of the depositary and except in the circumstances described in the prospectus supplement relating to the debt securities. The specific terms of the depositary arrangement with respect to a series of debt securities will be described in the prospectus supplement relating to such series.

Protection in the Event of Change of Control

Any provision in an indenture that governs our debt securities covered by this prospectus that includes any covenant or other provision providing for a put or increased interest or otherwise that would afford holders of our debt securities additional protection in the event of a recapitalization transaction, a change of control of our company, or a highly leveraged transaction will be described in the applicable prospectus supplement.

Covenants

Unless otherwise indicated in this prospectus or the applicable prospectus supplement, our debt securities may not have the benefit of any covenant that limits or restricts our business or operations, the pledging of our assets or the incurrence by us of indebtedness. We will describe in the applicable prospectus supplement any material covenants in respect of a series of debt securities.

Consolidation, Merger, Conveyance, Transfer or Lease

We may agree in any indenture that governs the debt securities of any series covered by this prospectus that we will not consolidate with or merge into any other person or convey, transfer or lease (as lessor) our properties and assets as, or substantially as, an entirety to any person, unless such person and such proposed transaction meets various criteria, which we will describe in detail in the applicable prospectus supplement.

Defaults and Notice

The debt securities of any series will contain events of default to be specified in the applicable prospectus supplement, which may include, without limitation:

If an event of default with respect to debt securities of any series shall occur and be continuing, we may agree that the trustee or the holders of at least 25% in aggregate principal amount of the then outstanding debt securities of such series may declare the principal amount (or, if the debt securities of such series are issued at an original issue discount, such portion of the principal amount as may be specified in the terms of the debt securities of such series) of all debt securities of such series or such other amount or amounts as the debt securities or supplemental indenture with respect to such series may provide, to be due and payable immediately. Any provisions pertaining to events of default and any remedies associated therewith will be described in the applicable prospectus supplement.

Any indenture that governs our debt securities covered by this prospectus may require that the trustee under such indenture shall, within 90 days after the occurrence of a default, give to holders of debt securities of any series notice of all uncured and unwaived defaults with respect to such series known to it. However, in the case of a default that results from the failure to make any payment of the principal of, premium, if any, or interest on the debt securities of any series, or in the payment of any sinking or purchase fund installment with respect to debt securities of such series, if any, the trustee may withhold such notice if it in good faith determines that

the withholding of such notice is in the interest of the holders of debt securities of such series. Any terms and provisions relating to the foregoing types of provisions will be described in further detail in the applicable prospectus supplement.

Any indenture that governs our debt securities covered by this prospectus will contain a provision entitling the trustee to be indemnified by holders of debt securities before proceeding to exercise any trust or power under the indenture at the request of such holders. Any such indenture may provide that the holders of at least a majority in aggregate principal amount of the then outstanding debt securities of any series may direct the time, method and place of conducting any proceedings for any remedy available to the trustee, or of exercising any trust or power conferred upon the trustee with respect to the debt securities of such series. However, the trustee under any such indenture may decline to follow any such direction if, among other reasons, the trustee determines in good faith that the actions or proceedings as directed may not lawfully be taken, would involve the trustee in personal liability or would be unduly prejudicial to the holders of the debt securities of such series not joining in such direction.

Any indenture that governs our debt securities covered by this prospectus may endow the holders of such debt securities to institute a proceeding with respect to such indenture, subject to certain conditions, which will be specified in the applicable prospectus supplement and which may include, that the holders of at least a majority in aggregate principal amount of the debt securities of such series then outstanding make a written request upon the trustee to exercise its power under the indenture, indemnify the trustee and afford the trustee reasonable opportunity to act. Even so, such holders may have an absolute right to receipt of the principal of or premium, if any, and interest when due, to require conversion or exchange of debt securities if such indenture provides for convertibility or exchangeability at the option of the holder and to institute suit for the enforcement of such rights. Any terms and provisions relating to the foregoing types of provisions will be described in further detail in the applicable prospectus supplement.

Modification of the Indenture

We and the trustee may modify any indenture that governs our debt securities of any series covered by this prospectus with or without the consent of the holders of such debt securities, under certain circumstances to be described in a prospectus supplement.

Defeasance; Satisfaction and Discharge

The prospectus supplement will outline the conditions under which we may elect to have certain of our obligations under the indenture discharged and under which the indenture obligations will be deemed to be satisfied.

Regarding the Trustee

We will identify the trustee and any relationship that we may have with such trustee, with respect to any series of debt securities, in the prospectus supplement relating to the applicable debt securities. You should note that if the trustee becomes a creditor of us, the indenture and the Trust Indenture Act of 1939 limit the rights of the trustee to obtain payment of claims in certain cases, or to realize on certain property received in respect of any such claim, as security or otherwise. The trustee and its affiliates may engage in, and will be permitted to continue to engage in, other transactions with us and our affiliates. If, however, the trustee acquires any “conflicting interest” within the meaning of the Trust Indenture Act of 1939, it must eliminate such conflict or resign.

Governing Law

The law governing the indenture and the debt securities will be identified in the prospectus supplement relating to the applicable indenture and debt securities.

DESCRIPTION OF OUR UNITS

The following description, together with the additional information we include in any applicable prospectus supplement, summarizes the material terms and provisions of the units that we may offer under this prospectus. Units may be offered independently or together with one or more of the securities that may be offered under this prospectus, in any combination, and may be attached to or separate from those securities. While the terms we have summarized below will generally apply to any future units that we may offer under this prospectus, we will describe the particular terms of any series of units that we may offer in more detail in the applicable prospectus supplement. The terms of any units offered under a prospectus supplement may differ from the terms described below.

The form of unit agreement, including a form of unit certificate, if any, will describe the terms of the series of units we may offer under this prospectus. The following summaries of material provisions of the units, and the unit agreements, are subject to, and qualified in their entirety by reference to, all the provisions of the unit agreement applicable to a particular series of units. We urge you to read the applicable prospectus supplements related to the units that we sell under this prospectus, as well as the complete unit agreements that contain the terms of the units.

General

We may issue units comprised of one or more of the securities that may be offered under this prospectus. Each unit will be issued so that the holder of the unit is also the holder of each security included in the unit. Thus, the holder of a unit will have the rights and obligations of a holder of each included security. The unit agreement under which a unit is issued may provide that the securities included in the unit may not be held or transferred separately, at any time or at any time before a specified date.

We will describe in the applicable prospectus supplement the terms of the series of units, including:

The provisions described in this section, as well as those described under “Description of Our Common Stock,” “Description of our Preferred Stock,” “Description of Our Debt Securities” and “Description of Our Warrants,” will apply to each unit and to any common stock, preferred stock, debt securities or warrants included in each unit, respectively.

Issuance in Series

We may issue units in such amounts and in numerous distinct series as we determine.

WHERE YOU CAN FIND MORE INFORMATION

We file annual, quarterly and current reports, proxy statements and other information with the SEC. The SEC maintains an internet website at www.sec.gov that contains reports, proxy and information statements, and other information regarding issuers that file electronically with the SEC. Copies of certain information filed by us with the SEC are also available on our website at www.perspectivetherapeutics.com. The inclusion of our website address is intended to be an inactive textual reference only and not an active hyperlink to our website. The information contained in, or that can be accessed through, our website address is not incorporated by reference in this prospectus and is not part of this prospectus.

INCORPORATION BY REFERENCE

The SEC allows us to “incorporate by reference” into this prospectus the information in other documents that we file with it. This means that we can disclose important information to you by referring you to those documents. The information incorporated by reference is considered to be a part of this prospectus, and information in documents that we file later with the SEC will automatically update and supersede information contained in documents filed earlier with the SEC or contained in this prospectus. We incorporate by reference in this prospectus (i) the documents listed below, (ii) all documents that we file with the SEC under Section 13(a), 13(c), 14 or 15(d) of the Exchange Act after the date of the initial filing of the registration statement of which this prospectus is included, and (iii) any future filings that we may make with the SEC under Sections 13(a), 13(c), 14, or 15(d) of the Exchange Act prior to the termination of the offering under this prospectus; provided, however, that we are not incorporating, in each case, any documents or information deemed to have been furnished and not filed, including any information that we disclose under Items 2.02 or 7.01 of any Current Report on Form 8-K, in accordance with SEC rules:

You may request, orally or in writing, a copy of any or all of the documents incorporated herein by reference. These documents will be provided to you at no cost by contacting: Perspective Therapeutics, Inc., Corporate Secretary, at 2401 Elliott Avenue, Suite 320, Seattle, Washington 98121 or (206) 676-0900. In addition, copies of any or all of the documents incorporated herein by reference may be accessed at our website at www.perspectivetherapeutics.com. The information contained in, or that can be accessed through, our website address is not incorporated by reference into this prospectus and is not a part of this prospectus.

LEGAL MATTERS

The validity of the issuance of the securities offered hereby will be passed upon for us by Hogan Lovells US LLP. As appropriate, legal counsel representing the underwriters, dealers or agents will be named in the accompanying prospectus supplement and may opine to certain legal matters.

EXPERTS

The financial statements incorporated in this prospectus by reference to the Annual Report on Form 10-K for the fiscal year ended December 31, 2023 have been so incorporated in reliance on the reports of Assure CPA, LLC, an independent registered public accounting firm, given on the authority of said firm as experts in auditing and accounting.

The financial statements incorporated in this prospectus by reference to the Annual Report on Form 10-K for the fiscal year ended December 31, 2024 have been so incorporated in reliance on the reports of WithumSmith+Brown, PC, an independent registered public accounting firm, given on the authority of said firm as experts in auditing and accounting.

$500,000,000

Common Stock

Preferred Stock

Warrants

Debt Securities

Units

PROSPECTUS

, 2025

The information contained in this prospectus is not complete and may be changed. These securities may not be sold until the registration statement filed with the Securities and Exchange Commission is effective. This prospectus is not an offer to sell these securities and it is not soliciting an offer to buy these securities in any jurisdiction where such offer or sale is not permitted.

SUBJECT TO COMPLETION, DATED MARCH 26, 2025

PROSPECTUS SUPPLEMENT

(To Prospectus dated March 26, 2025)

Up to $250,000,000

Common Stock

We have entered into a Controlled Equity OfferingSM Sales Agreement (the “Sales Agreement”), dated as of August 13, 2024, with Cantor Fitzgerald & Co. and RBC Capital Markets, LLC (each, an “Agent” and, collectively, the “Agents”), relating to the sale of shares of our common stock, par value $0.001 per share, offered by this prospectus supplement. In accordance with the terms of the Sales Agreement, under this prospectus supplement we may offer and sell shares of our common stock, $0.001 par value per share, having an aggregate offering price of up to $250,000,000 from time to time through or to the Agents, acting as our sales agents. As of the date of this prospectus, we have issued and sold shares of our common stock having an aggregate offering price of $10,205,718.54 pursuant to the prospectus supplement dated August 13, 2024. We will not make any further offers or sales of our common stock pursuant to the prior prospectus supplement and the accompanying prospectus.

Our common stock is listed on the NYSE American under the ticker symbol “CATX.” On March 24, 2025, the last reported sale price per share of our common stock was $2.52.

Sales of our common stock, if any, under this prospectus supplement may be made by any method deemed to be an “at the market offering” as defined in Rule 415(a)(4) promulgated under the Securities Act of 1933, as amended (the “Securities Act”). The Agents will act as our sales agents, using commercially reasonable efforts to sell on our behalf all of the shares of common stock requested to be sold by us, consistent with their normal trading and sales practices, on mutually agreed terms set forth in the Sales Agreement. There is no arrangement for funds to be received in any escrow, trust or similar arrangement.

The compensation to the Agents for sales of common stock sold pursuant to the Sales Agreement is an amount equal to up to 3.0% of the gross proceeds from the sale of shares through or to the applicable Agent. In connection with the sale of the common stock on our behalf, the Agents will be deemed to be “underwriters” within the meaning of the Securities Act, and the compensation of the Agents will be deemed to be underwriting commissions or discounts. We have also agreed to provide indemnification and contribution to the Agents with respect to certain liabilities, including liabilities under the Securities Act.

Investing in our securities involves a high degree of risk. See “Risk Factors” beginning on page S-4 of this prospectus supplement and elsewhere in this prospectus supplement, the accompanying prospectus and the other documents that are incorporated by reference in this prospectus supplement and the accompanying prospectus.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined if this prospectus supplement or the accompanying prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

Cantor RBC Capital Markets

The date of this prospectus supplement is , 2025.

TABLE OF CONTENTS

This prospectus supplement and the accompanying prospectus are part of a “shelf” registration statement on Form S-3 (File No. 333-279692) that we filed with the Securities and Exchange Commission (the “SEC”) on May 24, 2024 and amended on March 26, 2025. This document is in two parts. The first part is this prospectus supplement, which describes the terms of this offering of shares of our common stock and adds to and updates the information contained in the accompanying prospectus. The second part, the accompanying prospectus, provides more general information, some of which may not apply to this offering. Generally, when we refer to this prospectus, we are referring to both parts of this document combined. To the extent there is a conflict between the information contained in this prospectus supplement and the information contained in the accompanying prospectus, you should rely on the information in this prospectus supplement.

This prospectus supplement and the accompanying prospectus relate to the offering of shares of our common stock. Before buying any of the shares of common stock offered hereby, we urge you to read carefully this prospectus supplement and the accompanying prospectus, together with the information incorporated herein by reference as described below under the heading “Incorporation of Certain Information by Reference.” This prospectus supplement contains information about the common stock offered hereby and may add to, update or change information in the accompanying prospectus.

You should rely only on the information contained in, or incorporated by reference in, this prospectus supplement and the accompanying prospectus. We have not, and the Agents have not, authorized anyone to provide you with different or additional information.

We are not making offers to sell or solicitations to buy shares of our common stock in any jurisdiction in which an offer or solicitation is not authorized or in which the person making that offer or solicitation is not qualified to do so or to anyone to whom it is unlawful to make an offer or solicitation. You should assume that the information in this prospectus supplement and the accompanying prospectus is accurate only as of the date on the front of the respective document and that any information that we have incorporated by reference is accurate only as of the date of the document incorporated by reference, regardless of the time of delivery of this prospectus supplement or the accompanying prospectus or the time of any sale of shares of our common stock.

This prospectus supplement and the accompanying prospectus contain summaries of certain provisions contained in some of the documents described herein, but reference is made to the actual documents for complete information. All of the summaries are qualified in their entirety by the actual documents. Copies of some of the documents referred to herein have been filed, will be filed or will be incorporated herein by reference as exhibits to the registration statement, and you may obtain copies of those documents as described below under the section entitled “Where You Can Find More Information.”

We further note that the representations, warranties and covenants made by us in any agreement that is filed as an exhibit to any document that is incorporated by reference herein were made solely for the benefit of the parties to such agreement, including, in some cases, for the purpose of allocating risk among the parties to such agreements, and should not be deemed to be a representation, warranty or covenant to you. Moreover, such representations, warranties or covenants were accurate only as of the date when made. Accordingly, such representations, warranties and covenants should not be relied on as accurately representing the current state of our affairs.

This prospectus supplement and the accompanying prospectus contain and incorporate by reference market data and industry statistics and forecasts that are based on independent industry publications and other publicly-available information. Although we believe these sources are reliable, we do not guarantee the accuracy or completeness of this information and we have not independently verified this information. Although we are not aware of any misstatements regarding the market and industry data presented in this prospectus supplement, the accompanying prospectus or the documents incorporated herein by reference, these estimates involve risks and uncertainties and are subject to change based on various factors, including those discussed under the headings “Risk Factors” in this prospectus supplement

and the accompanying prospectus, and under similar headings in the other documents that are incorporated herein by reference. Accordingly, investors should not place undue reliance on this information.

Unless the context requires otherwise, in this prospectus supplement the terms “Perspective Therapeutics,” “the Company,” “we,” “us,” “our,” and similar terms refer to Perspective Therapeutics, Inc. and its wholly owned subsidiaries.

“Perspective Therapeutics” and the Perspective Therapeutics logo are our trademarks. This prospectus supplement and the accompanying prospectus and the documents incorporated by reference herein and therein may also contain trademarks and trade names that are the property of their respective owners. We do not intend our use or display of other companies’ trade names, trademarks or service marks to imply relationships with, or endorsements or sponsorship of us by, these other companies.

On June 14, 2024, we filed a Certificate of Amendment to our amended and restated certificate of incorporation with the Secretary of State of the State of Delaware to effect a 1-for-10 reverse stock split of our issued and outstanding shares of common stock, par value $0.001 per share, which became effective on June 14, 2024. All historical share and per share amounts reflected throughout this report have been adjusted to reflect the reverse stock split.

Investing in our common stock involves a high degree of risk. Before investing in our common stock, you should carefully consider the risks described below, together with all of the other information contained in this prospectus supplement and the accompanying prospectus and incorporated by reference herein and therein, including from our most recent Annual Report on Form 10-K and any subsequent Quarterly Reports on Form 10-Q or Current Reports on Form 8-K, as well as any amendments or update to our risk factors thereto reflected in subsequent filings with the SEC. Some of these factors relate principally to our business and the industry in which we operate. Other factors relate principally to your investment in our securities. The risks and uncertainties described therein and below are not the only risks that we face. Additional risks and uncertainties not presently known to us or that we currently deem immaterial may also materially and adversely affect our business and operations.

If any of the matters included in the following risks were to occur, our business, financial condition, results of operations, cash flows or prospects could be materially and adversely affected. In such case, you may lose all or part of your investment.

Risks Related to this Offering

A substantial number of shares of our common stock may be sold in the market following this offering, which may depress the market price for our common stock.

Sales of a substantial number of shares of our common stock in the public market following this offering could cause the market price of our common stock to decline. Although there can be no assurance that any of the $250 million worth of shares of our common stock being offered under this prospectus supplement will be sold or the price at which any such shares might be sold, assuming that an aggregate of 99,206,349 shares of our common stock are sold, for example, at a price of $2.52 per share, the last reported sale price of our common stock on the NYSE American on March 24, 2025, upon completion of this offering, based on our shares outstanding as of December 31, 2024, we will have outstanding an aggregate of 169,877,813 shares of common stock, assuming no exercise of our outstanding stock options or warrants. A substantial majority of the outstanding shares of our common stock are, and all of the shares of our common stock sold in this offering upon issuance will be, freely tradable without restriction or further registration under the Securities Act, unless these shares are owned or purchased by “affiliates” as that term is defined in Rule 144 under the Securities Act.

In addition, as of December 31, 2024, we had outstanding options to purchase 7,352,501 shares of our common stock at a weighted-average exercise price of $6.07 per share, outstanding common stock warrants to purchase 415,779 shares of our common stock at a weighted-average exercise price of $3.26, and outstanding pre-funded warrants to purchase 146,425 shares of our common stock at a weighted-average exercise price of $0.01. As of December 31, 2024, there were 4,910,871 shares of our common stock reserved for future issuance under our Third Amended and Restated 2020 Equity Incentive Plan, and an additional 3,533,573 shares of our common stock became reserved for future issuance under our Third Amended and Restated 2020 Equity Incentive Plan as of January 1, 2025. The shares of our common stock issuable under the Third Amended and Restated 2020 Equity Incentive Plan may be immediately eligible for resale in the open market. Such shares of our common stock, along with any other market transactions, could adversely affect the market price of our common stock. Additional dilution may result from the issuance of shares of our common stock in connection with additional financings or in connection with commercial transactions.

Moreover, if we issue options, restricted stock units, warrants or other securities to purchase or acquire our common stock in the future and those options, restricted stock units, warrants or other securities are exercised, converted or settled you may experience further dilution. Holders of shares of our common stock have no preemptive rights that entitle them to purchase their pro rata share of any offering of shares of any class or series.

You may experience additional dilution as a result of certain covenants related to our Investment Agreement with Lantheus.

Pursuant to that certain Investment Agreement (the “Investment Agreement”), dated January 8, 2024, between us and Lantheus Alpha Therapy, LLC (“Lantheus”), we are required to notify Lantheus within 10 business days of the end of a fiscal quarter in which we issued shares of our common stock pursuant to the Sales Agreement, of (i) the number of shares of Common Stock issued during such fiscal quarter pursuant to the Sales Agreement and (ii) the average price per share received by the Company before commissions (the “ATM Average Price”). Upon receipt of such notice, Lantheus may elect, at its option, to purchase all or a portion of its pro rata portion (as defined in the Investment Agreement) of the number of shares of our common stock issued pursuant to the Sales Agreement during such fiscal quarter at a price per share equal to the average price per share received by us before commissions. Pursuant to the Investment Agreement, Lantheus may not exercise this right more than two times per calendar year. If we issue shares of common stock pursuant to the Sales Agreement, and Lantheus subsequently elects to exercise its option, our existing stockholders will be diluted to the extent of the number of shares Lantheus purchases.

You may experience future dilution as a result of future equity offerings or other equity issuances.

In order to raise additional capital, we may in the future offer and issue additional shares of our common stock or other securities convertible into, exercisable or exchangeable for, or settled in, our common stock. We cannot assure you that we will be able to sell shares of our common stock or other securities in any other offering at a price per share that is equal to or greater than the price per share paid by investors in this offering, and investors purchasing shares or other securities in the future could have rights superior to existing stockholders. The price per share at which we sell additional shares of our common stock or other securities convertible into, exercisable or exchangeable for, or settled in, our common stock in future transactions may be higher or lower than the price per share in this offering. As of December 31, 2024, we had reserved 12,263,372 shares of our common stock for issuance upon the exercise of outstanding stock options and the issuance of awards available for grant under our equity incentive plans. An additional 3,533,573 shares of our common stock became reserved for future issuance under our Third Amended and Restated 2020 Equity Incentive Plan as of January 1, 2025. You will incur dilution upon the issuance of any shares of our common stock pursuant to such plans, upon vesting and settlement of any stock awards under any such plan, or upon exercise of any such outstanding options.

We have broad discretion in how we use the net proceeds of this offering and, despite our efforts, we may not use these net proceeds effectively or in ways with which you agree.

We intend to use the net proceeds from this offering for general corporate purposes and working capital. We may also use a portion of the net proceeds from this offering to acquire or invest in complementary businesses, technologies, product candidates or other intellectual property, although we have no present commitments or agreements to do so. However, we have not determined the specific allocation of the net proceeds among these potential uses. Our management will have broad discretion over the use and investment of the net proceeds of this offering, and, accordingly, investors in this offering will need to rely upon the judgment of our management with respect to the use of proceeds, with only limited information concerning our specific intentions. Our stockholders may not agree with the manner in which our management chooses to allocate and spend the net proceeds. Moreover, our management may use the net proceeds for corporate purposes that may not increase the market price of our common stock. Please see the section entitled “Use of Proceeds” on page S-8 of this prospectus supplement for further information.

We do not anticipate paying any cash dividends on our capital stock in the foreseeable future; accordingly, capital appreciation, if any, will be your sole source of gain and you may never receive a return on your investment.

We have never declared or paid cash dividends on our capital stock, and you should not rely on an investment in our common stock to provide dividend income. We currently intend to retain all of our future earnings, if any, to finance the growth and development of our business and do not anticipate declaring or paying any cash dividends for the foreseeable future. As a result, capital appreciation, if any, of our common stock will be your sole source of gain for the foreseeable future. Furthermore, we may in the future become subject to additional contractual restrictions on, or prohibitions against, the payment of dividends.

It is not possible to predict the aggregate proceeds resulting from sales made under the Sales Agreement, or the actual number of shares that we will issue under the Sales Agreement.

Subject to certain limitations in the Sales Agreement and compliance with applicable law, we have the discretion to deliver a placement notice to the Agents at any time throughout the term of the Sales Agreement. The number of shares of our common stock that are sold through the Agents after delivering a placement notice will fluctuate based on a number of factors, including the market price of our common stock during the sales period, any limits we may set with the Agents in any applicable placement notice and the demand for our common stock. Because this offering can be terminated at any time and the price per share of each share sold pursuant to the Sales Agreement will fluctuate over time, it is not currently possible to predict the aggregate proceeds to be raised or the number of shares of our common stock that will be issued in connection with sales under the Sales Agreement.

Sales of common stock offered hereby will be in “at the market offerings,” and investors who buy shares at different times will likely pay different prices.

Investors who purchase shares of our common stock in this offering at different times will likely pay different prices, and accordingly may experience different levels of dilution and different outcomes in their investment results. We will have discretion, subject to market demand, to vary the timing, prices and number of shares of our common stock sold in this offering. In addition, subject to the final determination by our board of directors or a committee thereof, or any restrictions we may place in any applicable placement notice delivered to the applicable Agent, there is no minimum or maximum sales price for shares of our common stock to be sold in this offering. Investors may experience a decline in the value of the shares of our common stock they purchase in this offering as a result of sales made at prices lower than the prices they paid.

This prospectus supplement and the documents incorporated by reference herein contain forward-looking statements that involve substantial risks and uncertainties. All statements, other than statements of historical facts, included in this prospectus supplement, the base prospectus or the documents incorporated herein and therein by reference, including statements regarding our future financial condition, results of operations, business strategy and plans and objectives of management for future operations, industry trends and other future events, are forward-looking statements. In some cases, you can identify forward-looking statements by terminology such as “may,” “anticipate,” “believe,” “could,” “expect,” “intend,” “might,” “plan,” “possible,” “potential,” “aim,” “predict,” “project,” “should,” “will,” “would” or the negative of these terms or other similar expressions, although not all forward-looking statements contain these identifying terms. The forward-looking statements in this prospectus supplement, the base prospectus and the documents incorporated herein and therein by reference include, among other things, statements about:

We may not actually achieve the plans, intentions or expectations disclosed in the forward-looking statements and you should not place undue reliance on the forward-looking statements. These forward-looking statements involve risks and uncertainties that could cause our actual results to differ materially from the results described in or implied by the forward-looking statements, including without limitation, the potential that regulatory authorities may not grant or may delay approval for our program candidates; uncertainties and delays relating to the design, enrollment, completion and results of clinical trials; unanticipated costs and expenses; early clinical trials may not be indicative of the results in later clinical trials; clinical trial results may not support regulatory approval or further development in a specified indication or at all; actions or advice of regulatory authorities may affect the design, initiation, timing, continuation and/or progress of clinical trials or result in the need for additional clinical trials; our ability to obtain and maintain regulatory approval for our program candidates; delays, interruptions or failures in the manufacture and supply of our program candidates; the size and growth potential of the markets for our program candidates, and our ability to service those markets; our cash and cash equivalents may not be sufficient to support our operating plan for as long as anticipated; our expectations, projections and estimates regarding expenses, future revenue, capital requirements, and the availability of and the need for additional financing; our ability to obtain additional funding to support our clinical development programs; the availability or potential availability of alternative products or treatments for conditions targeted by us that could affect the availability or commercial potential of our program candidates; our ability to manage growth and successfully integrate our businesses; whether we can retain our key employees; whether there is sufficient training and use of our programs and program candidates; the market acceptance and recognition of our programs and program candidates; our ability to maintain and enforce our intellectual property rights; whether we can maintain our therapeutic isotope supply agreement with the Department of Energy; whether we will continue to comply with the procedures and regulatory requirements mandated by the Food and Drug Administration for additional trials, Phase 1 and 2 approvals, Fast Track approvals, and 510(k) approval and reimbursement codes; and any changes in applicable laws and regulations. Other factors that may cause our actual results to differ materially from those expressed or implied in the forward-looking statements are described under the heading “Risk Factors” in our most recent Annual Report on Form 10-K and our most recent Quarterly Report on Form 10-Q, each filed with the SEC, in our other filings with the SEC, and in our future reports to be filed with the SEC and available at www.sec.gov.

Should known or unknown risks materialize, or should underlying assumptions prove inaccurate, actual results could differ materially from past results and those anticipated, estimated or projected in the forward-looking statements. You should bear this in mind as you consider any forward-looking statements.

You should read this prospectus supplement, the base prospectus and the documents that we incorporate by reference herein and therein completely and with the understanding that our actual future results may be materially different from what we expect. The forward-looking statements contained in this prospectus supplement are made as

of the date of this prospectus supplement, and we undertake no duty to update such forward-looking statements, whether as a result of new information, future events or otherwise, except as required by applicable law.

We may issue and sell shares of common stock having aggregate sales proceeds of up to $250 million from time to time, before deducting sales agent commissions and expenses. The amount of proceeds from this offering will depend upon the number of shares of our common stock sold and the market price at which they are sold. There can be no assurance that we will be able to sell any shares of our common stock under or fully utilize the Sales Agreement as a source of financing.

We intend to use the net proceeds from this offering for general corporate purposes, which may include research and development expenditures, preclinical study and clinical trial expenditures, manufacturing expenditures, commercialization expenditures, working capital, capital expenditures, acquisitions of new technologies, products or businesses and investments. We may also use a portion of the net proceeds from this offering to acquire or invest in complementary businesses, technologies, product candidates or other intellectual property, although we have no present commitments or agreements to do so.

The amounts and timing of our use of the net proceeds from this offering will depend on a number of factors, such as the timing and progress of our research and development efforts, the timing and progress of any partnering efforts, technological advances and the competitive environment for our product candidates. As of the date of this prospectus supplement, we cannot specify with certainty all of the particular uses for the net proceeds to us from the sale of the shares of common stock offered by us hereunder. Accordingly, our management will have broad discretion in the timing and application of these proceeds. Pending application of the net proceeds as described above, we intend to temporarily invest the proceeds in short-term, interest-bearing instruments.

We have entered into a Controlled Equity OfferingSM Sales Agreement (the “Sales Agreement”) with Cantor Fitzgerald & Co. and RBC Capital Markets, LLC (together, the “Agents”). Pursuant to this prospectus supplement, we may offer and sell shares of our common stock having an aggregate gross sales price of up to $250,000,000 from time to time through the Agents acting as sales agents. A copy of the Sales Agreement was filed as an exhibit to a Current Report on Form 8-K filed with the SEC on August 14, 2024 and is incorporated by reference into this prospectus supplement.

Upon delivery of a placement notice and subject to the terms and conditions of the Sales Agreement, the Agents may sell shares of our common stock by any method permitted by law deemed to be an “at the market offering” as defined in Rule 415(a)(4) promulgated under the Securities Act. We may instruct the Agents not to sell common stock if the sales cannot be effected at or above the price designated by us from time to time. We or the Agents may suspend the offering of common stock upon notice and subject to other conditions.

Each time we wish to issue and sell shares of common stock under the Sales Agreement, we will notify an Agent (the “Designated Agent”) of the number of shares to be issued, the dates on which such sales are anticipated to be made, any limitation on the number of shares to be sold in any one day and any minimum price below which sales may not be made. Once we have so instructed the Designated Agent, unless the Agent declines to accept the terms of such notice, the Designated Agent has agreed to use its commercially reasonable efforts, consistent with its normal sales and trading practices, to solicit offers to purchase the common stock under the terms and subject to the conditions set forth in the Sales Agreement.

We will pay the Designated Agent commissions, in cash, for its service in acting as agent in the sale of our common stock. The Designated Agent will be entitled to compensation at a commission rate of up to 3.0% of the sales price per share sold under the Sales Agreement. Because there is no minimum offering amount required as a condition to close this offering, the actual total public offering amount, commissions and proceeds to us, if any, are not determinable at this time. We have also agreed to reimburse the Agents for certain specified expenses, including the fees and disbursements of their legal counsel in an amount not to exceed (a) $75,000 in connection with the execution of the Sales Agreement, (b) $25,000 per calendar quarter thereafter pursuant to the terms of the Sales Agreement, and (c) $40,000 for each program “refresh” (filing of a new registration statement, prospectus or prospectus supplement relating to shares of our common stock and/or an amendment of the Sales Agreement) executed pursuant to the Sales Agreement. We estimate that the total expenses for the offering, excluding compensation and reimbursements payable to the Agents under the terms of the Sales Agreement, will be approximately $415,000.

Settlement for sales of shares of our common stock will occur on the first business day following the date on which any sales are made, or on some other date that is agreed upon by us and the Designated Agent in connection with a particular transaction, in return for payment of the net proceeds to us. Sales of our common stock as contemplated in this prospectus supplement will be settled through the facilities of The Depository Trust Company or by such other means as we and the Agents may agree upon. There is no arrangement for funds to be received in an escrow, trust or similar arrangement.

In connection with the sale of the common stock on our behalf, the Designated Agent will be deemed to be an “underwriter” within the meaning of the Securities Act and the compensation of the Designated Agent will be deemed to be underwriting commissions or discounts. We have agreed to provide indemnification and contribution to the Agents against certain civil liabilities, including liabilities under the Securities Act.

The offering of shares of our common stock pursuant to the Sales Agreement will terminate upon the termination of the Sales Agreement as permitted therein. We and each Agent may terminate the Sales Agreement at any time upon five days’ prior notice.

The Agents and their affiliates may in the future provide various investment banking, commercial banking and other financial services for us and our affiliates, for which services they may in the future receive customary fees. To the extent required by Regulation M, the Agents will not engage in any market making activities involving our common stock while the offering is ongoing under this prospectus supplement.

This prospectus supplement and the accompanying prospectus may be made available in electronic format on a website maintained by the Agents, and the Agents may distribute this prospectus supplement and the accompanying prospectus electronically.

The validity of the shares of our common stock we are offering will be passed upon by Hogan Lovells US LLP. Mintz, Levin, Cohn, Ferris, Glovsky and Popeo, P.C., New York, New York has acted as counsel to the Agents in connection with this offering.

The financial statements incorporated in this prospectus by reference to the Annual Report on Form 10-K for the fiscal year ended December 31, 2023 have been so incorporated in reliance on the reports of Assure CPA, LLC, an independent registered public accounting firm, given on the authority of said firm as experts in auditing and accounting.

The financial statements incorporated in this prospectus by reference to the Annual Report on Form 10-K for the fiscal year ended December 31, 2024 have been so incorporated in reliance on the reports of WithumSmith+Brown, PC, an independent registered public accounting firm, given on the authority of said firm as experts in auditing and accounting.

With respect to the statements contained in this prospectus supplement regarding the contents of any agreement or any other document, in each instance, the statement is qualified in all respects by the complete text of the agreement or document, a copy of which has been filed as an exhibit to the registration statement.

Because we are subject to the information and reporting requirements of the Exchange Act, we file annual, quarterly and current reports, proxy statements and other information with the SEC. Our SEC filings are available to the public over the Internet at the SEC’s website at www.sec.gov.

We make available free of charge on our website at www.perspectivetherapeutics.com our annual, quarterly and current reports, including amendments to such reports, as soon as reasonably practicable after we electronically file such material with, or furnish such material to, the SEC. Please note, however, that we have not incorporated any other information by reference from our website, other than the documents listed under the heading “Incorporation of Certain Information by Reference” on page S-11 of this prospectus supplement. In addition, you may request copies of these filings at no cost by writing or telephoning us at the following address or telephone number:

Perspective Therapeutics, Inc.

2401 Elliott Avenue, Suite 320

Seattle, Washington 98121

Telephone: (206) 676-0900

We have filed with the SEC a registration statement on Form S-3 under the Securities Act, of which this prospectus supplement forms a part. The rules and regulations of the SEC allow us to omit from this prospectus supplement certain information included in the registration statement. For further information about us and the securities we are offering under this prospectus, you should refer to the registration statement and the exhibits and schedules filed with the registration statement. The SEC allows us to “incorporate by reference” information into this prospectus supplement. This means that we can disclose important information to you by referring you to other documents we have filed separately with the SEC, without actually including the specific information in this prospectus supplement. The information incorporated by reference is considered to be part of this prospectus supplement, and information that we file later with the SEC (and that is deemed to be “filed” with the SEC) will automatically update, and may supersede, information in this prospectus supplement.

• our Annual Report on Form 10-K for the fiscal year ended December 31, 2024, filed with the SEC on March 26, 2025;

• our definitive proxy statement on Schedule 14A, filed with the SEC on April 18, 2024 (other than information furnished rather than filed);

• our Current Reports on Form 8-K, filed with the SEC on January 6, 2025, January 13, 2025, January 24, 2025, February 3, 2025, March 4, 2025, March 17, 2025, and March 26, 2025; and

• the description of our common stock contained in our Registration Statement on Form 8-A filed on April 12, 2007, as updated by Exhibit 4.1 to our Annual Report on Form 10-K for the fiscal year ended December 31, 2024, including any amendments or reports filed for the purpose of updating such description.

All reports and other documents subsequently filed by us pursuant to Sections 13(a), 13(c), 14 and 15(d) of the Exchange Act after the date of this prospectus supplement and prior to the termination or completion of the offering of securities under this prospectus supplement shall be deemed to be incorporated by reference in this prospectus supplement and to be a part hereof from the date of filing such reports and other documents.

To obtain copies of these filings, see “Where You Can Find More Information” on page S-11 of this prospectus supplement.

Up to $250,000,000

Common Stock

PROSPECTUS SUPPLEMENT

Cantor RBC Capital Markets

, 2025

PART II

INFORMATION NOT REQUIRED IN THE PROSPECTUS

Item 14. Other Expenses of Issuance and Distribution.

Set forth below is an estimate of the amount of fees and expenses to be incurred in connection with the issuance and distribution of the offered securities registered hereby, other than underwriting discounts and commission, if any, incurred in connection with the sale of the offered securities. All such amounts will be borne by Perspective Therapeutics, Inc.

Item 15. Indemnification of Directors and Officers.

Section 102 of the Delaware General Corporation Law, or the DGCL, permits a corporation to eliminate the personal liability of its directors or its stockholders for monetary damages for a breach of fiduciary duty as a director, except where the director breached his or her duty of loyalty, failed to act in good faith, engaged in intentional misconduct or knowingly violated a law, authorized the payment of a dividend or approved a stock repurchase in violation of Delaware corporate law or obtained an improper personal benefit. Our certificate of incorporation provides that no director shall be personally liable to us or our stockholders for monetary damages for any breach of fiduciary duty as a director, notwithstanding any provision of law imposing such liability, except to the extent that the DGCL prohibits the elimination or limitation of liability of directors for breaches of fiduciary duty.

Section 145 of the DGCL provides that a corporation has the power to indemnify a director, officer, employee or agent of the corporation and certain other persons serving at the request of the corporation in related capacities against expenses (including attorneys’ fees), judgments, fines and amounts paid in settlements actually and reasonably incurred by the person in connection with an action, suit or proceeding to which he or she is or is threatened to be made a party by reason of such position, if such person acted in good faith and in a manner he or she reasonably believed to be in or not opposed to the best interests of the corporation, and, in any criminal action or proceeding, had no reasonable cause to believe his or her conduct was unlawful, except that, in the case of actions brought by or in the right of the corporation, no indemnification shall be made with respect to any claim, issue or matter as to which such person shall have been adjudged to be liable to the corporation unless and only to the extent that the Court of Chancery or other adjudicating court determines that, despite the adjudication of liability but in view of all of the circumstances of the case, such person is fairly and reasonably entitled to indemnification for such expenses which the Court of Chancery or such other court shall deem proper.

As permitted by the DGCL, our Certificate of Incorporation provides that: (i) we shall indemnify and hold harmless our directors and officers against all liability and loss suffered and expenses reasonably incurred to the fullest extent permitted by the DGCL; (ii) we shall, upon satisfaction of certain conditions, advance the expenses incurred by our directors and officers in connection with certain legal proceedings; (iii) the indemnification rights conferred in

the Certificate of Incorporation are not exclusive; and (iv) we are authorized to enter into indemnification agreements with our directors and officers.

We have entered into or expect to enter into indemnification agreements with each of our directors and executive officers which require us to indemnify them against expenses, judgments, penalties, fines and amounts paid in settlement actually and reasonably incurred by such person in connection with any proceeding, whether actual or threatened, to which such person may be made a party by reason of the fact that such person is or was a director or officer of the Company or any of our affiliates, provided such person acted in good faith and in a manner such person reasonably believed to be in, or not opposed to, our best interests. The indemnification agreements also set forth certain procedures that will apply in the event of a claim for indemnification thereunder.

We maintain a directors’ and officers’ liability insurance policy. The policy insures directors and officers against unindemnified losses arising from certain wrongful acts in their capacities as directors and officers and reimburses us for those losses for which we have lawfully indemnified the directors and officers. The policy contains various exclusions.

Insofar as indemnification for liabilities arising under the Securities Act may be permitted for our directors, executive officers or persons controlling us, we have been informed that, in the opinion of the SEC, such indemnification is against public policy as expressed in the Securities Act and is therefore unenforceable.

Item 16. Exhibits and Financial Statement Schedules.

* To be filed, if necessary, subsequent to the effectiveness of this registration statement by an amendment to this registration statement or incorporated by reference pursuant to a Current Report on Form 8-K in connection with an offering of securities.

** To be filed in accordance with the requirements of Section 305(b)(2) of the Trust Indenture Act of 1939 and Rule 5b-3 thereunder.

Item 17. Undertakings.

(a) The undersigned registrant hereby undertakes:

(1) To file, during any period in which offers or sales are being made, a post-effective amendment to this registration statement:

(i) To include any prospectus required by section 10(a)(3) of the Securities Act of 1933;

(ii) To reflect in the prospectus any facts or events arising after the effective date of the registration statement (or the most recent post-effective amendment thereof) which, individually or in the aggregate, represent a fundamental change in the information set forth in the registration statement. Notwithstanding the foregoing, any increase or decrease in volume of securities offered (if the total dollar value of securities offered would not exceed that which was registered) and any deviation from the low or high end of the estimated maximum offering range may be reflected in the form of prospectus filed with the SEC pursuant to Rule 424(b) if, in the aggregate, the changes in volume and price represent no more than a 20% change in the maximum aggregate offering price set forth in the “Calculation of Registration Fee” table in the effective registration statement; and

(iii) To include any material information with respect to the plan of distribution not previously disclosed in the registration statement or any material change to such information in the registration statement;

provided, however, that paragraphs (i), (ii) and (iii) do not apply if the registration statement is on Form S-3 and the information required to be included in a post-effective amendment by those paragraphs is contained in reports filed with or furnished to the SEC by the registrant pursuant to Section 13 or Section 15(d) of the Exchange Act that are incorporated by reference in the registration statement, or is contained in a form of prospectus filed pursuant to Rule 424(b) that is part of the registration statement.

(2) That, for the purpose of determining any liability under the Securities Act of 1933, each such post-effective amendment shall be deemed to be a new registration statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof.

(3) To remove from registration by means of a post-effective amendment any of the securities being registered which remain unsold at the termination of the offering;

(5) That, for the purpose of determining liability under the Securities Act of 1933 to any purchaser:

(i) Each prospectus filed by the registrant pursuant to Rule 424(b)(3) shall be deemed to be part of the registration statement as of the date the filed prospectus was deemed part of and included in the registration statement; and

(ii) Each prospectus required to be filed pursuant to Rule 424(b)(2), (b)(5) or (b)(7) as part of a registration statement in reliance on Rule 430B relating to an offering made pursuant to Rule 415(a)(1)(i), (vii) or (x) for the purpose of providing the information required by Section 10(a) of the Securities Act of 1933 shall be deemed to be part of and included in the registration statement as of the earlier of the date such form of prospectus is first used after effectiveness or the date of the first contract of sale of securities in the offering described in the prospectus. As provided in Rule 430B, for liability purposes of the issuer and any person that is at that date an underwriter, such date shall be deemed to be a new effective date of the registration statement relating to the securities in the registration statement to which the prospectus relates, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof. Provided, however, that no statement made in a registration statement or prospectus that is part of the registration statement or made in a document incorporated or deemed incorporated by reference into the registration statement or prospectus that is part of the registration statement will, as to a purchaser with a time of contract of sale prior to such effective date, supersede or modify any statement that was made in the registration statement or prospectus that was part of the registration statement or made in any such document immediately prior to such effective date; and

(6) That, for the purpose of determining liability of the registrant under the Securities Act of 1933 to any purchaser in the initial distribution of the securities, the undersigned registrant undertakes that in a primary offering of securities of the undersigned registrant pursuant to this registration statement, regardless of the underwriting method used to sell the securities to the purchaser, if the securities are offered or sold to such purchaser by means of any of the following communications, the undersigned registrant will be a seller to the purchaser and will be considered to offer or sell such securities to such purchaser:

(i) Any preliminary prospectus or prospectus of the undersigned registrant relating to the offering required to be filed pursuant to Rule 424;

(ii) Any free writing prospectus relating to the offering prepared by or on behalf of the undersigned registrant or used or referred to by the undersigned registrant;

(iii) The portion of any other free writing prospectus relating to the offering containing material information about the undersigned registrant or its securities provided by or on behalf of the undersigned registrant; and

(iv) Any other communication that is an offer in the offering made by the undersigned registrant to the purchaser.

(b) The undersigned registrant hereby undertakes that, for purposes of determining any liability under the Securities Act of 1933, each filing of the registrant’s annual report pursuant to Section 13(a) or Section 15(d) of the Exchange Act that is incorporated by reference in this registration statement shall be deemed to be a new registration statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof.

(h) Insofar as indemnification for liabilities arising under the Securities Act of 1933 may be permitted to directors, officers and controlling persons of the registrant pursuant to the foregoing provisions, or otherwise, the registrant has been advised that in the opinion of the Securities and Exchange Commission such indemnification is against public policy as expressed in the Act and is, therefore, unenforceable. In the event that a claim for indemnification against such liabilities (other than the payment by the registrant of expenses incurred or paid by a director, officer or controlling person of the registrant in the successful defense of any action, suit or proceeding) is asserted by such director, officer or controlling person in connection with the securities being registered, the registrant will, unless in the opinion of its counsel the matter has been settled by controlling precedent, submit to a court of appropriate jurisdiction the question whether such indemnification by it is against public policy as expressed in the Act and will be governed by the final adjudication of such issue.

(j) If and when applicable, the undersigned registrant hereby undertakes to file an application for the purpose of determining the eligibility of the trustee to act under subsection (a) of Section 310 of the Trust Indenture Act in accordance with the rules and regulations prescribed by the Securities and Exchange Commission under Section 305(b)(2) of the Act.

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, as amended, the registrant certifies that it has reasonable grounds to believe that it meets all of the requirements for filing on Form S-3 and has duly caused this Post-Effective Amendment No. 2 to the registration statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the city of Seattle, State of Washington, on this 26th day of March, 2025.

Pursuant to the requirements of the Securities Act of 1933, as amended, this Post-Effective Amendment No.2 to the registration statement has been signed by the following persons in the capacities and on the dates indicated.