SEC Form SC 13G/A filed by Spero Therapeutics Inc. (Amendment)

 UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13G

(Rule 13d-102)

INFORMATION TO BE INCLUDED IN STATEMENTS FILED PURSUANT

TO RULES 13d-1(b), (c), AND (d) AND AMENDMENTS THERETO FILED

PURSUANT TO RULE 13d-2(b)

(Amendment No. 4)¹

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

1              The remainder of this cover page shall be filled out for a reporting person’s initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter disclosures provided in a prior cover page.

The information required on the remainder of this cover page shall not be deemed to be “filed” for the purpose of Section 18 of the Securities Exchange Act of 1934 (“Act”) or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

(1) Includes 493,000 shares of Common Stock (defined below) currently issuable upon the conversion of certain Series B Preferred (defined below).

Includes 887,905 shares of Common Stock currently issuable upon the conversion of certain Series C Preferred (defined below).

(1) Includes 493,000 shares of Common Stock currently issuable upon the conversion of certain Series B Preferred.

Includes 887,905 shares of Common Stock currently issuable upon the conversion of certain Series C Preferred.

(1) Includes 385,000 shares of Common Stock currently issuable upon the conversion of certain Series B Preferred.

(1) Includes 385,000 shares of Common Stock currently issuable upon the conversion of certain Series B Preferred.

(1) Includes 60,000 shares of Common Stock currently issuable upon the conversion of certain Series B Preferred.

(1) Includes 60,000 shares of Common Stock currently issuable upon the conversion of certain Series B Preferred.

(1) Includes 878,000 shares of Common Stock currently issuable upon the conversion of certain Series B Preferred.

Includes 887,905 shares of Common Stock currently issuable upon the conversion of certain Series C Preferred.

(1) Includes 938,000 shares of Common Stock currently issuable upon the conversion of certain Series B Preferred.

Includes 887,905 shares of Common Stock currently issuable upon the conversion of certain Series C Preferred.

(1) Includes 938,000 shares of Common Stock currently issuable upon the conversion of certain Series B Preferred.

Includes 887,905 shares of Common Stock currently issuable upon the conversion of certain Series C Preferred.

(1) Includes 938,000 shares of Common Stock currently issuable upon the conversion of certain Series B Preferred.

Includes 887,905 shares of Common Stock currently issuable upon the conversion of certain Series C Preferred.

Spero Therapeutics, Inc., a Delaware corporation (the “Issuer”).

675 Massachusetts Avenue, 14th Floor

Cambridge, Massachusetts 02139

Biotechnology Value Fund, L.P. (“BVF”)

44 Montgomery St., 40th Floor

San Francisco, California 94104

Citizenship: Delaware

BVF I GP LLC (“BVF GP”)

44 Montgomery St., 40th Floor

San Francisco, California 94104

Citizenship: Delaware

Biotechnology Value Fund II, L.P. (“BVF2”)

44 Montgomery St., 40th Floor

San Francisco, California 94104

Citizenship: Delaware

BVF II GP LLC (“BVF2 GP”)

44 Montgomery St., 40th Floor

San Francisco, California 94104

Citizenship: Delaware

Biotechnology Value Trading Fund OS LP (“Trading Fund OS”)

PO Box 309 Ugland House

Grand Cayman, KY1-1104

Cayman Islands

Citizenship: Cayman Islands

BVF Partners OS Ltd. (“Partners OS”)

PO Box 309 Ugland House

Grand Cayman, KY1-1104

Cayman Islands

Citizenship: Cayman Islands

BVF GP Holdings LLC (“BVF GPH”)

44 Montgomery St., 40th Floor

San Francisco, California 94104

Citizenship: Delaware

BVF Partners L.P. (“Partners”)

44 Montgomery St., 40th Floor

San Francisco, California 94104

Citizenship: Delaware

BVF Inc.

44 Montgomery St., 40th Floor

San Francisco, California 94104

Citizenship: Delaware

Mark N. Lampert (“Mr. Lampert”)

44 Montgomery St., 40th Floor

San Francisco, California 94104

Citizenship: United States

Each of the foregoing is referred to as a “Reporting Person” and collectively as the “Reporting Persons.”

Common Stock, $0.001 par value (the “Common Stock”)

84833T103

As of the close of business on December 31, 2021, the Reporting Persons held 938 shares of Series B Convertible Preferred Stock (the “Series B Preferred”), convertible for an aggregate of 938,000 shares of Common Stock. The Series B Preferred may not be converted if, after such conversion, the Reporting Persons would beneficially own, as determined in accordance with Section 13(d) of the Securities Exchange Act of 1934 (the “Exchange Act”), more than 9.99% of the number of shares of Common Stock then issued and outstanding (the “Series B Blocker”). As of the close of business on December 31, 2021, the Series B Blocker does not limit the conversion of the Series B Preferred owned by the Reporting Person.

As of the close of business on December 31, 2021, the Reporting Persons held 2,214 shares of Series C Convertible Preferred Stock (the “Series C Preferred”) convertible for an aggregate of 2,214,000 shares of Common Stock. The Series C Preferred may not be converted if, after such conversion, the Reporting Persons would beneficially own, as determined in accordance with Section 13(d) Exchange Act, more than 9.99% of the number of shares of Common Stock then issued and outstanding (the “Series C Blocker”). As of the close of business on December 31, 2021, the Series C Blocker limits the aggregate conversion of Series C Preferred by the Reporting Persons to 887,905 out of the 2,214,000 shares of Common Stock underlying the Series C Preferred owned by the Reporting Persons in the aggregate.

As of the close of business on December 31, 2021, the Reporting Persons held 3,215,000 shares of Series D Convertible Preferred Stock (the “Series D Preferred”) convertible for an aggregate of 3,215,000 shares of Common Stock. The Series D Preferred may not be converted if, after such conversion, the Reporting Persons would beneficially own, as determined in accordance with Section 13(d) Exchange Act, more than 9.99% of the number of shares of Common Stock then issued and outstanding (the “Series D Blocker” and together with the Series B Blocker and Series C Blocker, the “Beneficial Ownership Limitation”). As of the close of business on December 31, 2021, the Series D Blocker limits the aggregate conversion of Series D Preferred by the Reporting Persons to 0 out of the 3,215,000 shares of Common Stock underlying the Series D Preferred owned by the Reporting Persons in the aggregate.

The Reporting Persons may choose to convert the Series B Preferred, Series C Preferred or Series D Preferred in other amounts among the Reporting Persons, while continuing to comply with the Beneficial Ownership Limitation.

As of the close of business on December 31, 2021 (i) BVF beneficially owned 2,169,102 shares of Common Stock, including 493,000 shares of Common Stock issuable upon the conversion of certain Series B Preferred held by it and 887,905 shares of Common Stock issuable upon the conversion of certain Series C Preferred held by it, and excluding 278,095 shares of Common Stock underlying certain Series C Preferred held by it and 1,801,109 shares of Common Stock underlying certain Series D Preferred held by it, (ii) BVF2 beneficially owned 1,001,264 shares of Common Stock, including 385,000 shares of Common Stock issuable upon the conversion of certain Series B Preferred held by it, and excluding 889,000 shares of Common Stock underlying certain Series C Preferred held by it and 1,205,542 shares of Common Stock underlying certain Series D Preferred held by it, and (iii) Trading Fund OS beneficially owned 106,154 shares of Common Stock, including 60,000 shares of Common Stock issuable upon conversion of certain Series B Preferred held by it, and excluding 159,000 shares of Common Stock underlying certain Series C Preferred held by it and 208,349 shares of Common Stock underlying certain Series D Preferred held by it.

BVF GP, as the general partner of BVF, may be deemed to beneficially own the 2,169,102 shares of Common Stock beneficially owned by BVF.

BVF2 GP, as the general partner of BVF2, may be deemed to beneficially own the 1,001,264 shares of Common Stock beneficially owned by BVF2.

Partners OS, as the general partner of Trading Fund OS, may be deemed to beneficially own the 106,154 shares of Common Stock beneficially owned by Trading Fund OS.

BVF GPH, as the sole member of each of BVF GP and BVF2 GP, may be deemed to beneficially own the 3,170,366 shares of Common Stock beneficially owned by BVF and BV2.

Partners, as the investment manager of BVF, BVF2 and Trading Fund OS, and the sole member of Partners OS, may be deemed to beneficially own the 3,411,520 shares of Common Stock beneficially owned in the aggregate by BVF, BVF2 and Trading Fund OS and held in a certain Partners managed account (the “Partners Managed Account”), including 135,000 shares of Common Stock held in the Partners Managed Account.

BVF Inc., as the general partner of Partners, may be deemed to beneficially own the 3,411,520 shares of Common Stock beneficially owned by Partners.

Mr. Lampert, as a director and officer of BVF Inc., may be deemed to beneficially own the 3,411,520 shares of Common Stock beneficially owned by BVF Inc.

The foregoing should not be construed in and of itself as an admission by any Reporting Person as to beneficial ownership of any shares of Common Stock owned by another Reporting Person. BVF GP disclaims beneficial ownership of the shares of Common Stock beneficially owned by BVF. BVF2 GP disclaims beneficial ownership of the shares of Common Stock beneficially owned by BVF2. Partners OS disclaims beneficial ownership of the shares of Common Stock beneficially owned by Trading Fund OS. BVF GPH disclaims beneficial ownership of the shares of Common Stock beneficially owned by BVF and BVF2. Each of Partners, BVF Inc. and Mr. Lampert disclaims beneficial ownership of the shares of Common Stock beneficially owned by BVF, BVF2 and Trading Fund OS and held in the Partners Managed Account, and the filing of this statement shall not be construed as an admission that any such person or entity is the beneficial owner of any such securities.

The following percentages are based on a denominator that is the sum of (i) 32,323,617 shares of Common Stock outstanding, as of November 5, 2021, as disclosed in the Issuer’s Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission on November 10, 2021, (ii) certain or all of the 938,000 shares of Common Stock issuable upon the conversion of certain Series B Preferred, as applicable and (iii) certain of the 887,905 shares of Common Stock issuable upon the conversion of certain Series C Preferred, as applicable.

As of the close of business on December 31, 2021 (i) BVF beneficially owned approximately 6.4% of the outstanding shares of Common Stock, (ii) BVF2 beneficially owned approximately 3.1% of the outstanding shares of Common Stock, (iii) Trading Fund OS beneficially owned less than 1% of the outstanding shares of Common Stock, (iv) BVF GP may be deemed to beneficially own approximately 6.4% of the outstanding shares of Common Stock, (v) BVF2 GP may be deemed to beneficially own approximately 3.1% of the outstanding shares of Common Stock, (vi) Partners OS may be deemed to beneficially own less than 1% of the outstanding shares of Common Stock, (vii) BVF GPH may be deemed to beneficially own approximately 9.3% of the outstanding shares of Common Stock, and (v) each of Partners, BVF Inc. and Mr. Lampert may be deemed to beneficially own approximately 9.99% of the outstanding shares of Common Stock (less than 1% of which is held in the Partners Managed Account).

See Cover Pages Items 5-9.

See Cover Pages Items 5-9.

See Cover Pages Items 5-9.

See Cover Pages Items 5-9.

Not Applicable.

BVF GP, BVF GPH, Partners, BVF Inc. and Mr. Lampert share voting and dispositive power over the shares of Common Stock beneficially owned by BVF. BVF GPH, Partners, BVF Inc. and Mr. Lampert share voting and dispositive power over the shares of Common Stock beneficially owned by BVF2. Partners, BVF Inc. and Mr. Lampert share voting and dispositive power over the shares of Common Stock beneficially owned by BVF, BVF2 and Trading Fund OS and held in the Partners Managed Account.

Not Applicable.

See Exhibit 99.1 to Amendment No. 2 to the Schedule 13G filed with the Securities and Exchange Commission on February 18, 2020.

Not Applicable.

By signing below each of the undersigned certifies that, to the best of its knowledge and belief, the securities referred to above were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect.

SIGNATURE

After reasonable inquiry and to the best of his knowledge and belief, each of the undersigned certifies that the information set forth in this statement is true, complete and correct.

Dated: February 14, 2022