TIMELY INFORMATION INSIDE

Global Dynamic Income Fund (CHW)

SEMIANNUAL REPORT APRIL 30, 2019

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You may elect to receive all future reports in paper free of charge. You can inform the Fund that you wish to continue receiving paper copies of your shareholder reports by calling 800.582.6959. If you own these shares through a financial intermediary, you may contact your financial intermediary or follow instructions included with this disclosure to elect to continue to receive paper copies of your shareholder reports. Your election to receive reports in paper will apply to all funds held with the fund complex or your financial intermediary.

  

TABLE OF CONTENTS

Letter to Shareholders1

The Calamos Closed-End Funds:
An Overview5

Investment Team Discussion6

Schedule of Investments10

Statement of Assets and Liabilities24

Statement of Operations25

Statements of Changes In Net Assets26

Statement of Cash Flows27

Notes to Financial Statements28

Financial Highlights37

Report of Independent Registered
Public Accounting Firm38

About Closed-End Funds39

Managed Distribution Policy40

Automatic Dividend Reinvestment Plan40

Experience and Foresight

Our Managed Distribution Policy

Closed-end fund investors often seek a steady stream of income. Recognizing this important need, Calamos closed-end funds adhere to a managed distribution policy in which we aim to provide consistent monthly distributions through the disbursement of the following:

•Net investment income

•Net realized short-term capital gains

•Net realized long-term capital gains

•And, if necessary, return of capital

We set distributions at levels that we believe are sustainable for the long term. The Fund’s current monthly distribution rate is $0.0700 per share. Our team focuses on delivering an attractive monthly distribution, while maintaining a long-term emphasis on risk management. The level of the Fund’s distribution can be greatly influenced by market conditions, including the interest rate environment, the individual performance of securities held by the funds, our view of retaining leverage, fund tax considerations, and regulatory requirements.

You should not draw any conclusions about the Fund’s investment performance from the amount of its distribution or from the terms of the Fund’s plan. The Fund’s Board of Trustees may amend or terminate the managed distribution policy at any time without prior notice to the Fund’s shareholders. However, at this time there are no reasonably foreseeable circumstances that might cause the termination of the Fund’s managed distribution policy.

For more information about any Calamos closed-end funds, we encourage you to contact your financial advisor or Calamos Investments at 800.582.6959 (Monday through Friday from 8:00 a.m. to 6:00 p.m., Central Time). You can also visit us at www.calamos.com.

Note: The Fund adopted a managed distribution policy on January 1, 2018.

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-month period ended April 30, 2019. In this report, you will find commentary from the Calamos portfolio management teams, as well as a listing of portfolio holdings, financial statements and highlights, and detailed information about the performance and positioning of the Calamos Fund.

Distribution

During the period, the Fund provided a compelling monthly distribution of $0.0700 per share. We believe the Fund’s current annualized distribution rate, which was 10.06%*on a market price basis as of April 30, 2019, was very competitive, given the low interest rates in many segments of the bond market. In our view, the Fund’s distributions illustrate the benefits of a multi-asset class approach and flexible allocation strategy.

We understand that many closed-end fund investors seek steady, predictable distributions instead of distributions that fluctuate. Therefore, this Fund has a managed distribution policy. As part of this policy, we aim to keep distributions consistent from month to month, and at a level that we believe can be sustained over the long term. In setting the Fund’s distribution rate, the investment management team and the Fund’s Board of Trustees consider the interest rate, market and economic environment. We also factor in our assessment of individual securities and asset classes.

Market Review

During the semiannual period, broad stock market barometers posted strong results, both in the U.S. and globally.¹ Convertible securities rose briskly,² and high yield corporate and investment-grade bond markets advanced at a more measured but still healthy pace.³

*Current Annualized Distribution Rate is the Fund’s most recent distribution, expressed as an annualized percentage of the Fund’s current market price per share. The Fund’s 4/30/19 distribution was $0.0700 per share. Based on our current estimates, we anticipate that approximately $0.0137 is paid from ordinary income or capital gains and that approximately $0.0563 represents a return of capital. Estimates are calculated on a tax basis rather than on a generally accepted accounting principles (GAAP) basis, but should not be used for tax reporting purposes. Distributions are subject to re-characterization for tax purposes after the end of the fiscal year. This information is not legal or tax advice. Consult a professional regarding your specific legal or tax matters. Under the Fund’s managed distribution policy, distributions paid to common shareholders may include net investment income, net realized short-term and long-term capital gains and return of capital. When the net investment income and net realized short-term and long-term capital gains are not sufficient, a portion of the distribution will be a return of capital. The distribution rate may vary.

2   CALAMOS Global Dynamic Income Fund SEMIANNUAL REPORT

However, the six-month period was extremely volatile, with Federal Reserve policy, trade disputes, and growth concerns driving sharp swings in investor sentiment. During the final months of 2018, markets sold off steeply. Investors worried the Federal Reserve would derail the U.S. economic recovery and hinder global growth by raising short-term rates too quickly. Trade uncertainty and global economic data further unsettled market participants.

The tide of negative sentiment quickly turned in late December as comments from the Federal Reserve alleviated concerns about additional tightening. U.S. economic data continued to be healthy and financial conditions improved. The global growth outlook brightened, helped by a contained U.S. dollar, optimism about an eventual resolution to global trade disputes, and data supporting the view that China’s economy could achieve a soft landing. Against this backdrop, stocks, convertible securities and high yield bonds rallied dramatically through the end of the reporting period.

Outlook

We believe there is still real fundamental strength in the U.S. economy, as fiscal policy provides a wind in the sails for businesses. Unemployment is low, inflation is contained and corporate earnings are healthy. Consumers can continue to fuel growth, as they benefit from wage growth, manageable debt levels and employment gains. The Federal Reserve has affirmed its commitment to maintaining a patient approach to short-term interest rates.

Outside the U.S., economic data looks more encouraging than it did at the start of 2019. We may well see a pickup in the second half of the year, with accommodative global monetary policy, a contained dollar and U.S. growth providing tailwinds. Of course, the path of U.S.-China trade policy will influence what we see next, but a resolution is not out of reach.

Ongoing economic growth sets the stage for additional upside in stocks, convertible securities and high yield bonds. Yet, despite the favorable economic backdrop, we believe investors should be prepared for persistent volatility and episodic selloffs, such as the downturn that occurred in May of 2019 in the stock and high yield markets. A variety of political and geopolitical uncertainties—including tensions in the Middle East, election unknowns, and trade—are likely to stoke turbulence.

CALAMOS Global Dynamic Income Fund SEMIANNUAL REPORT   3

Asset allocation for long-term goals

Elevated volatility can be an unwelcomed prospect for investors. However, the flipside of volatility is opportunity. I have invested through many periods of market turmoil: the 1973–1974 crash, Black Monday in 1987, and the collapse of the dot.com bubble, to name just a few. In all of these markets, there were opportunities—to sell into strength or to pick up an attractive position at a lower price. Our investment teams are following just such an approach, drawing on Calamos Investments’ decades of proprietary research and risk-management strategies.

As I’ve discussed in past letters to shareholders, repositioning your portfolio quickly in response to short-term market changes can be a dangerous strategy. Far too often, investors catch the downside in the market, only to be on the sidelines when markets rally. Instead, I encourage you to work with your financial advisor to ensure that your investment portfolio reflects your risk tolerance and investment goals. With the right funds at the core of an allocation, it may be easier to stay invested through short-term volatility.

Conclusion

Thank you for your continued trust in Calamos Investments. We look forward to helping you pursue your financial objectives in the years to come.

Sincerely,

John P. Calamos, Sr.

Founder, Chairman and Global Chief Investment Officer

4   CALAMOS Global Dynamic Income Fund SEMIANNUAL REPORT

CALAMOS Global Dynamic Income Fund SEMIANNUAL REPORT   5

In our closed-end funds, we draw upon decades of investment experience, including a long history of opportunistically blending asset classes in an attempt to capture upside potential while seeking to manage downside risk. We launched our first closed-end fund in 2002.

Closed-end funds are long-term investments. Most focus on providing monthly distributions, but there are important differences among individual closed-end funds. Calamos closed-end funds can be grouped into multiple categories that seek to produce income while offering exposure to various asset classes and sectors.

6   CALAMOS Global Dynamic Income Fund SEMIANNUAL REPORT

TOTAL RETURN* AS OF 4/30/19

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 product that seeks to provide an attractive monthly distribution 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 multiple asset classes. We utilize a highly flexible approach by investing in equities, convertible securities and high yield bonds. We may also employ a “covered call” strategy to both mitigate equity risk and enhance income opportunities. We may also employ an alternative strategy such as 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 that we are well positioned to generate income and capital gains. The broader range of security types also provides us with increased opportunities to manage the risk/reward characteristics of the portfolio over full market cycles. For the period, our participation in equity markets was beneficial to the overall performance of the Fund.

We invest in both U.S. and non-U.S. companies, with at least 40% of assets invested in foreign corporations. We emphasize companies with reliable debt servicing, respectable balance sheets and sustainable prospects for growth. 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 reporting period?

The Fund returned 9.83% on a net asset value (NAV) basis for the six-month period ended April 30, 2019. On a market price basis, the Fund returned 16.31%. For the sake of comparison to the broader global markets, the MSCI EAFE Index returned 7.73%, the MSCI World Index returned 9.16%, and the S&P 500 Index gained 9.76% during the period.

At the end of the reporting period, the Fund’s shares traded at a 0.72% premium to NAV.

How do NAV and market price return differ?

Closed-end funds trade on exchanges, where the price of shares may be driven by factors other than the value of the underlying securities. The price of a share in the market is called market value. Market price can be influenced by factors unrelated to the performance of the fund’s holdings, such as general market sentiment or future expectations. A fund’s NAV return measures the actual return of the individual securities in the portfolio, less fund expenses. It also measures how a manager was able to capitalize on market opportunities. Because we believe closed-end funds are best utilized long term within asset allocations, we believe that NAV return is the better measure of a fund’s performance. However, when managing the fund, we strongly consider actions and policies that we believe will optimize its overall price performance and returns based on market price.

CALAMOS Global Dynamic Income Fund SEMIANNUAL REPORT   7

SINCE INCEPTION MARKET PRICE AND NAV HISTORY THROUGH 4/30/19

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.

Please discuss the Fund’s distributions during the six-month period.

Within this Fund, we employ a managed distribution policy with the goal of providing shareholders a consistent distribution stream. In each month of the period, the Fund distributed $0.0700 per share, resulting in a current annualized distribution rate of 10.06% of market price as of April 30, 2019.

We believe that both the Fund’s distribution rate and level remained attractive and competitive, as low interest rates limited yield opportunities in much of the marketplace. For example, as of April 30, 2019, the dividend yield of S&P 500 Index stocks averaged approximately 1.92%. Yields also were low within the U.S. government bond market, with the 10-year U.S. Treasury and 30-year U.S. Treasury yielding 2.51% and 2.93%, respectively.

What factors influenced performance over the reporting period?

The Fund has the ability to invest in a range of strategies including convertible securities, high yield, U.S. equities, international equities and convertible arbitrage. This enables us to participate in a myriad of opportunities on behalf of our shareholders. Given this flexibility, we were able to maintain our exposure to the equity markets through our convertible holdings, which allowed us to participate in the general upward trajectory of equities in a risk-managed manner. Broad improvements in both domestic and global equity and fixed income markets contributed to the Fund’s strong performance over the period. Price performance was enhanced by good valuations in the stock relative to the NAV earlier in the period, which served as an enticement to many investors.

The Fund’s U.S. equity sleeve underperformed relative to the S&P 500 Index, as selection in communication services (specifically a slight overweight and selection in interactive media & services) contributed to performance. In addition, our selection and underweight in health care (biotechnology) was additive.

Conversely, our overweight and selection in energy (oil & gas equipment & services) impeded performance relative to the index. In addition, our selection and underweight in industrials (namely railroads selection) was not helpful.

The Fund’s global equity sleeve underperformed relative to the MSCI World Index. Our selection and overweight in information technology (namely an overweight in application software) was helpful. Our selection in energy, namely oil and gas exploration and production, also proved beneficial.

8   CALAMOS Global Dynamic Income Fund SEMIANNUAL REPORT

On the flipside, our selection in real estate (specifically in real estate operating companies) weighed on performance. In addition, our selection in consumer discretionary, specifically in automobile manufacturers, also weighed on results.

The Fund’s international sleeve outperformed relative to the MSCI EAFE Index. Our underweight and selection in financials (asset management & custody banks) was beneficial relative to the index. Selection in consumer discretionary (namely an overweight in home furnishing retail) was also helpful.

Conversely, selection in information technology (overweight in communications equipment) impeded performance relative to the MSCI EAFE Index. In addition, our selection in industrials (notably in electrical components & equipment) hindered return.

Convertible Arbitrage entails owning a convertible bond long and then shorting its underlying stock. It is employed as a strategy to enhance returns. The convertible arbitrage portion of the Fund contributed positive monthly results, even when the market dropped dramatically in December.

After hiking interest rates four times during the previous fiscal year, the Federal Reserve hiked interest rates once again in December before pausing. As investors grew wary of a Fed that might overtighten, the Fed announced that it had revised its expectation to zero additional 2019 rate increases, and it would reduce the amount of balance sheet normalization—in this environment interest rates declined. The 3-year U.S. Treasury yield declined from 2.93% to 2.24%, while the 5-year U.S. Treasury yield moved from 2.98% to 2.28%. The 10-year U.S. Treasury yield declined from 3.15% to 2.51%. Credit spreads finished the period largely where they began with JPMorgan reporting a 3 basis points spread contraction to 418 basis points over U.S. Treasuries during the period.

Rising interest rates provided mixed results for convertible arbitrage during the period. From a positive standpoint, the 25 basis points increase to the fed funds rate in December meant that the overnight interest received on the cash received from our short stock positions moves higher. From a challenging standpoint, higher interest rates held back the bond value of our long convertible holdings.

Though the CBOE Volatility Index (VIX) declined from 22.23 at the beginning of the period to 13.11 at the end, it reached a high of 36.07 on December 24. The volatility was beneficial to the fund in terms of increased opportunities for rebalancing in convertible arbitrage.

Cheapening convertible valuations were a drag on the convertible arbitrage strategy toward period end. The average convertible in the ICE BofAML All U.S. Convertible Index (VXA0) traded at a 2.15% average discount, cheaper than the 1.59% discount at the beginning of the reporting period.

How is the Fund positioned?

We continued to find opportunities across asset classes. We maintained a preference for larger-cap, growth-oriented companies with global presence and geographically diversified revenue streams. We believe that such companies are well positioned to capitalize on the global and U.S. growth trends we see. In keeping with an emphasis on risk management, we focus on companies that we believe have respectable balance sheets, solid free cash flows, reliable debt servicing, and good prospects for sustainable growth as a result of consumer confidence and income.

CALAMOS Global Dynamic Income Fund SEMIANNUAL REPORT   9

The portfolio’s largest allocations—in absolute terms—are found in the information technology, communication services and financial sectors. We believe that many information technology companies offer compelling fundamentals and participation in secular growth trends. Likewise, they are beneficiaries of the health of the U.S. consumer. Concerning communication services, we believe that companies in the sector should benefit from higher employment, improved consumer sentiment and relatively low interest rates. In addition, we believe that our exposure to financial companies will do well in a lower regulatory environment and one that is supported by a healthy U.S. consumer. Conversely, we are maintaining relatively low exposures to utilities and real estate, which we believe are fully valued at this point in the cycle.

As noted, we pursue a risk-managed approach to total return. This said, the portfolio includes a blend of high yield and investment grade credits. We take a very selective approach to CCC-rated credits. Given our view that economic growth should be closely monitored, we believe it is particularly important to favor companies that offer the best prospects for reliable debt servicing.

We believe that this is an environment that is conducive to the prudent use of leverage as a means of enhancing total return and supporting the Fund’s distribution rate. Over the period, in spite of a cost increase due to rising interest rates in 2018, our use of leverage enjoyed a favorable reinvestment dynamic for our shareholders. As of April 30, 2019, our amount of leveraged assets was approximately 33%.

What are your closing thoughts for Fund shareholders?

Given our outlook for a continued period of moderate economic growth, at least in the short-term, we favor quality growth companies over cyclicals. Favorable factors within the U.S. include solid job creation, low interest rates, healthy consumer confidence and income, limited inflationary pressures. We are emphasizing investments in companies with solid cash flow generation and stronger balance sheets. From a thematic and sector perspective, we see opportunities in the technology sector, consumer discretionary companies tied to U.S. and global consumption, and companies positioned to benefit from improving fundamentals. We are also optimistic about financials, as we believe that many of these companies are favorably valued and positioned to grow revenues based on lower regulations and a healthy U.S. consumer. We are also cautious about companies in the real estate and utilities sectors. We believe they may be fully valued as investors seek those stocks for income rather than growth. We are selective regarding the health care sector, favoring diversified companies that are more product growth-oriented versus those relying on pricing to achieve earning growth. We believe our active, risk-managed investment approach positions us to take advantage of the volatility, as well as opportunities in global equities and convertible securities.

We believe that fiscal policy and geopolitical concerns are likely to remain a focal point of market anxiety. However, we also believe that the Fed’s policy will try to be accommodative toward fiscal growth in spite of their desire to normalize interest rates by market factors as opposed to stimulus. In our view, equities continue to offer compelling risk/reward characteristics, as we seek companies that have attractively valued fundamentals and are benefiting from the wealth and continued confidence of the U.S. consumer. That said, ongoing risk assessment through an actively managed portfolio is imperative during times of continued market volatility to optimize returns.