SEC Form N-CSRS filed by Calamos Global Dynamic Income Fund

TIMELY INFORMATION INSIDE

Global Dynamic Income Fund (CHW)

SEMIANNUAL REPORT APRIL 30, 2023

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CALAMOS CLOSED-END FUNDS

Innovative Solutions for
the Search for Income

About Calamos Investments:

•An innovator in dynamically allocated closed-end funds since 2002

•Funds offer competitive distributions through our multi-asset class approach and strategies that have been less dependent on interest rates

•Total return and enhanced fixed income funds can meet a range of investor needs

•Distribution policies seek to provide steady monthly income

•Currently managing $7.8 billion in seven closed-end funds*

*As of 4/30/2023.

TABLE OF CONTENTS

John P. calamos, sr.

Founder, Chairman
and Global Chief
Investment Officer

CALAMOS Global Dynamic Income Fund SEMIANNUAL REPORT   1

Dear Fellow Shareholder:

Welcome to your semiannual report for the six months ending April 30, 2023. In this report, you will find commentary from our portfolio management team, a listing of portfolio holdings, financial statements and highlights, and detailed information about the performance and positioning of Calamos Global Dynamic Income Fund (CHW).

Innovative Multi-Asset Approach Supports the Search for Steady, Attractive Income

Our experience with closed-end funds dates back to 2002, and we have always recognized that many investors choose closed-end funds to support their search for income. Like all our closed-end funds, CHW is managed to provide steady (although not assured) monthly distributions. As of April 30, 2023, the monthly per share distribution was $0.0500, and the annualized distribution rate was 10.15%† on market price. In comparison, the dividend yield of S&P 500 Index stocks was 1.66%. Yields were also still relatively low within the US government bond market with the 10-year US Treasury yielding 3.45% at period end. Therefore, the Fund’s annualized distribution rate has soundly outdistanced both fixed income and equity alternatives.

Market Review and Outlook

For the period, stock markets around the world advanced. Market participants were encouraged by the prospect that the Federal Reserve would slow or pause its tightening cycle and by economic data that was often better than initially feared. Looking abroad, investors cheered the economic reopening in China.

In a reversal of fortunes from 2022, growth stocks outperformed their value counterparts by a wide margin. Technology and communication services companies, including many of the bellwether companies that struggled in 2022, dominated market leadership. Many areas of the fixed income market also posted healthy gains, with both investment grade and high yield benchmarks advancing.

2   CALAMOS Global Dynamic Income Fund SEMIANNUAL REPORT

Despite these advances, the period was also volatile. The failures of Silicon Valley Bank in the US and Credit Suisse overseas created a burst of fear and raised the specter of widespread bank runs. However, coordinated action by regulators and other large banks quickly dampened anxiety. Inflation has been another key focal point of investor concern. We expect inflation to continue to moderate through the summer months in an on-again, off-again fashion, punctuated by bouts of volatility in oil prices.

Despite economic and market uncertainties, we continue to see many opportunities across asset classes. We believe individual security selection and active management are essential, given the economic backdrop. In the “Investment Team Discussion,” our portfolio managers discuss where they see opportunities and how they are managing risk.

Perspectives on Asset Allocation

I’m often asked what I believe are the “secrets” of investing. It’s an easy question to answer—there are no secrets. However, there are some basic principles that I believe can best position investors for success.

One of the most fundamental principles is to stay focused on the long term. Trying to predict the short-term ups and downs in the market is a dangerous strategy. Far too often, I’ve seen people give in to emotions, which can result in selling into down markets but missing the up markets.

Another essential principle is diversification. Various investments tend to perform differently depending on interest rates, inflation, or the economic environment. The performance of investments can also be influenced by fiscal policy, political uncertainty, and the geopolitical landscape. Having a blend of assets can help smooth the performance of your portfolio because stronger returns in one area of your portfolio can offset weaker results elsewhere.

For investors who seek equity exposure with lower downside volatility, we believe CHW continues to be a strong choice for several reasons:

•Our ability to dynamically adjust the allocations of stocks, convertible bonds, and high yield securities—in addition to using alternative strategies—enables us to deftly manage the risk/reward characteristics of the portfolio over full market cycles.

•We look beyond the short-term noise to identify pockets of opportunity among innovative companies with quality fundamentals, those in thematic niches, and those that can demonstrate long-term resilience regardless of the macro backdrop.

•In a rising-interest-rate environment, price-to-earnings multiples can come down even if earnings are good, so our team remains mindful of valuations.

CALAMOS Global Dynamic Income Fund SEMIANNUAL REPORT   3

Conclusion

As always, we thank you for your continued trust. To learn more about Calamos Investments’ views of the economy, markets and asset allocation, I invite you to visit our website, www.calamos.com.

Sincerely,

John P. Calamos, Sr.

Founder, Chairman and Global Chief Investment Officer

4   CALAMOS Global Dynamic Income Fund SEMIANNUAL REPORT

Enhanced Fixed-Income and Total-Return Strategies

Calamos closed-end funds draw upon decades of our pioneering experience, including a long history of opportunistically blending asset classes in an attempt to capture upside potential while seeking to manage downside risk. Our closed-end funds can be broadly grouped into two categories: enhanced fixed income and total return. The funds share a focus on producing income while offering exposure to various asset classes and sectors.

CALAMOS Global Dynamic Income Fund SEMIANNUAL REPORT   5

AVERAGE ANNUAL TOTAL RETURN^† AS OF 4/30/23

Performance data quoted represents past performance, which is no guarantee of future results. Current performance may be lower or higher than the performance quoted. The principal value and investment return of an investment will fluctuate so that your shares, when redeemed, may be worth more or less than their original cost. Average annual total return measures net investment income and capital gain or loss from portfolio investments as an annualized average. All performance shown assumes reinvestment of dividends and capital gain distributions. Source: State Street Corporation and Morningstar Direct.

† Average annual total return measures net investment income and capital gain or loss from portfolio investments as an annualized average assuming reinvestment of dividends and capital gains distributions.

NOTES:

The 40%ACWI(NR)-30%RefinitivGlblCv-30%BBGHY2%Cap Index is blended from 40% - MSCI ACWI Index (Net), 30% - Refinitiv Global Convertible Bond Index and 30% - Bloomberg US Corporate High Yield 2% Issuer Capped Index.

The MSCI ACWI Index (Net) is a free float-adjusted market-capitalization-weighted index that is designed to measure the equity market performance of developed markets and emerging markets. The index is calculated in both US dollars and local currencies. Net return basis approximates the minimum possible reinvestment of regular cash distributions by deducting withholding tax based on the maximum rate of the company’s country of incorporation applicable to institutional investors.

The Refinitiv Global Convertible Bond Index (USD) is designed to represent the global convertible market.

The Bloomberg US Corporate High Yield 2% Issuer Capped Index measures the performance of high-yield corporate bonds with a maximum allocation of 2% to any one issuer.

Index returns assume reinvestment of dividends and do not reflect deduction of fees and expenses. It is not possible to invest directly in an index.

6   CALAMOS Global Dynamic Income Fund SEMIANNUAL REPORT

TOTAL RETURN* AS OF 4/30/2023

SECTOR WEIGHTINGS

Sector weightings are based on managed assets and may vary over time. Sector Weightings exclude any government/sovereign bonds or options on broad market indexes the Fund may hold.

GLOBAL DYNAMIC INCOME FUND (CHW)

INVESTMENT TEAM DISCUSSION

Please discuss the Fund’s strategy and role within an asset allocation.

Calamos Global Dynamic Income Fund (CHW) is a global enhanced fixed-income offering that seeks to generate a high level of current income with a secondary objective of capital appreciation. We believe the Fund offers a diversified way to participate in the long-term potential of global markets.

In this portfolio, we draw upon our team’s wide-ranging experience in an array of asset classes. We utilize a highly flexible approach to investing in equities, convertible securities and high-yield securities. We also can employ alternative strategies such as covered call writing and convertible arbitrage. Through covered call writing, we seek to generate income by selling (“writing”) options on market indexes. In the convertible arbitrage strategy, we invest in convertible securities and short sell the convertibles’ underlying equities to generate income and hedge against risk.

We believe that this broad mandate enhances our ability to capitalize on market volatility, manage potential downside risks, and generate more income versus traditional fixed-income funds. The allocation to each asset class and strategy is dynamic, reflecting our view of the economic landscape and the potential of individual securities. By combining asset classes and strategies, we believe the Fund is well positioned to generate income and capital gains. The broader range of security types also provides increased opportunities to manage the risk/reward characteristics of the portfolio over full market cycles.

We invest in both US and non-US companies, with at least 40% of assets invested in non-US companies. We emphasize companies with reliable debt servicing, respectable balance sheets and sustainable growth prospects. Regardless of a company’s country of domicile, we favor companies with geographically diversified revenue streams and global business strategies.

How did the Fund perform over the semiannual period?

The Fund returned 12.85% on a net asset value (NAV) basis and 10.15% on a market price basis for the six months ended April 30, 2023 (“semiannual period”), versus a return of 8.98% for a comparator index comprising 40% MSCI ACWI Index, 30% Refinitiv Global Convertible Bond Index, and 30% Bloomberg US Corporate High Yield 2% Issuer Capped Index. At the end of the semiannual period, the Fund’s shares traded at a 10.05% discount to NAV.

How do NAV and market price returns differ?

Closed-end funds trade on exchanges where factors other than the value of underlying securities can drive the price of shares. The price of a share in the market is called market value. Factors unrelated to the performance of the Fund’s holdings, such as general market sentiment or future expectations, may influence the market price. A fund’s NAV return measures the actual return of the individual securities in the portfolio, less fund expenses; it also measures how a portfolio manager capitalized on market opportunities. Because we believe closed-end funds are best used long term within asset allocations, we think that NAV return is the better measure of a fund’s performance. However, when managing the Fund, we strongly consider actions and policies that have the potential to optimize overall price performance and returns based on the market value.

CALAMOS Global Dynamic Income Fund SEMIANNUAL REPORT   7

Please discuss the Fund’s distributions during the reporting period.

We employ a level rate distribution policy within this Fund with the goal of providing shareholders with a consistent distribution stream. The Fund’s monthly distribution on April 30, 2023, was $0.0500 per share, resulting in an annualized distribution rate of 10.15% of the market price as of April 30, 2023.

We believe both the Fund’s distribution rate and level remained attractive and competitive because low but rising interest rates limited yield opportunities in much of the marketplace. For example, as of April 30, 2023, the dividend yield of S&P 500 Index stocks was 1.66%. Although higher than a year ago, yields within the US government bond market were also still relatively low at the end of the period with the 10-year US Treasury yielding 3.45%.

What factors influenced performance over the period?

Global stocks experienced significant volatility and rotation but generated positive returns over the semiannual period. Investors navigated multiple environments characterized by tighter monetary policy and turmoil in the global banking sector, but also signs of moderating inflation and resilient corporate earnings.

In addition, Federal Reserve activities continued with further rate increases over the period, raising short-term levels three times in the aggregate of 100 basis points between December and March. This brought the target rate to 4.75%–5.00% at the end of the period. The lead-up expectations and execution of higher interest rates by the Fed fostered overall volatility in financial markets.

In the pursuit of our risk-managed equity objective, the Fund navigated choppy markets by actively employing a blend of common stocks, convertibles and options Our holdings in convertible securities provided diversification but lagged the gains of a select group of large caps (or relatively defensive companies). Over the extended multi-year market cycle that began in 2020, however, our wider universe of stocks and convertible securities has been instrumental in managing the risk/reward profile and delivering compelling total returns.

SINCE INCEPTION MARKET PRICE AND NAV HISTORY THROUGH 4/30/2023

Performance data quoted represents past performance, which is no guarantee of future results. Current performance may be lower or higher than the performance quoted. The principal value of an investment will fluctuate so that your shares, when sold, may be worth more or less than their original cost. Returns at NAV reflect the deduction of the Fund’s management fee, debt leverage costs and all other applicable fees and expenses. You can obtain performance data current to the most recent month end by visiting www.calamos.com.

8   CALAMOS Global Dynamic Income Fund SEMIANNUAL REPORT

Other factors that affected Fund performance included the following:

•Despite increasing financing costs over the period, our use of leverage helped returns because our reinvestment rate, especially in equities, was greater than our associated costs thanks to the overall broad financial market improvements. Although leverage can enhance returns during favorable markets, the opposite can occur during unfavorable conditions.

•On an unleveraged basis, the portfolio outperformed the comparator index during the period. Our overweight and selection in equities and underweight in corporate bonds benefited returns relative to the index, whereas our selection of convertible bonds and use of put options detracted from returns.

•Selection in the information technology sector, notably in the semiconductors industry, contributed to returns relative to the comparator index. In addition, selection in the health care sector, primarily in pharmaceuticals, was helpful.

•Conversely, our selection in the oil & gas drilling industry within the energy sector weighed on results relative to the comparator index as did our internet and direct marketing retail industry names within the consumer discretionary sector.

•From a country perspective, our selection in the US proved beneficial to performance relative to the comparator index. Conversely, our overweight in China dragged on results.

How is the Fund positioned?

The Fund’s regional and country positioning reflects the combined inputs from our top-down global framework and our bottom-up security analysis. Our investment team evaluates macroeconomic factors and growth opportunities and actively integrates them into the investment decision-making process. To tap into selective growth potential in the global economy, we favor growth companies with quality balance sheets, strong brands, free cash flows and experienced management—businesses poised to withstand market volatility.

In terms of Fund positioning, we emphasize companies with favorable pricing power, strong earnings momentum, quality balance sheets, and attractive valuations. Zooming out, information technology, consumer discretionary and financials are among the largest sector weights in the Fund. Key industry positions include pharmaceuticals semiconductors, diversified banks, interactive media & services, systems software and automobile manufacturers. We own a range of holdings in energy and materials, spanning companies positioned to benefit from favorable supply-and-demand dynamics and attractive capital efficiency. We are underweight in defensive sectors, including utilities, real estate, consumer staples and more traditional telecoms.

•Through a geographic lens, our largest exposure is the US (approximately 51%) where we see a range of attractive bottom-up opportunities across secular growth, cyclicals, and select defensives, reflecting our view of earnings growth and advantaged business models.

•We own diverse holdings in Europe (approximately 19%) where we maintain a blend of secular growth, defensives and select commodities. We continue to evaluate the outlook across Europe given the ongoing war in Ukraine and tightening monetary conditions, although the region’s links to global demand benefited from the broader post-pandemic reopening.

CALAMOS Global Dynamic Income Fund SEMIANNUAL REPORT   9

•We own a range of holdings in emerging markets (approximately 22%). Our positioning reflects our sanguine view of China’s sustained reopening, the US dollar and global monetary policy, and relative valuations. We own positions within key industries including semiconductors, interactive media and higher-quality financials.

•We own multiple positions in Japan (approximately 3%) with attractive business models that offer exposure to secular growth, cyclicals and reopening dynamics.

The average credit quality of the portfolio is BB. As of April 30, 2023, the Fund has approximately 12% of its rated assets in investment-grade securities. Our credit process tends to guide us away from the most speculative corporate securities. That said, we recognize that opportunities are available for lower-credit securities to enhance performance.

We are cognizant of rising interest rates and inflation. Although the Fund invests primarily in equities, the weighted average duration of the bonds in our portfolio is only 2.5 years as of April 30, 2023. This relatively low-duration average is expected to help mitigate the volatility that our fixed-income securities might incur in a rising-rate environment.

We believe the prudent use of leverage may enhance total return and support the Fund’s distribution rate over the long term. As of April 30, 2023, our amount of leveraged assets was approximately 26%.

What are your closing thoughts for Fund shareholders?

Global markets continue to reflect a set of complex crosscurrents. Therefore, we are analyzing many aspects of economic activity, including evolving policy actions, corporate earnings, and the geopolitical backdrop. Considering tighter global monetary policy and mixed inflation dynamics, the financial markets remain uncertain, and we expect volatility to continue until these risks resolve. Within this complicated backdrop, we continue seeking ways to capitalize on volatility, including opportunities at the thematic, regional and market-cap levels. Because markets must navigate geopolitical risks, monetary policy and inflation, we believe the Fund’s focus on providing lower-volatility global equity market participation over full market cycles will serve it well.