FORMN-CSR CERTIFIED SHAREHOLDER REPORT OF REGISTEREDMANAGEMENT INVESTMENT COMPANIES Investment Company Act file number811-21969 Date of fiscal year end:December 31 Date of reporting period:December 31, 2024 Form N-CSR is to be used by management investment companies to file reports with the Commission not later than 10 days after the transmission tostockholders of any report that is required to be transmitted to stockholders under Rule30e-1 under the Investment Company Act of 1940 (17 CFR270.30e-1). The Commission may use the information provided on Form N-CSR in its regulatory, disclosure review, inspection, and policymaking roles. A registrant is required to disclose the information specified by Form N-CSR, and the Commission will make this information public. A registrant is notrequired to respond to the collection of information contained in Form N-CSR unless the Form displays a currently valid Office of Management andBudget (“OMB”) control number. Please direct comments concerning the accuracy of the information collection burden estimate and any suggestions forreducing the burden to Secretary, Securities and Exchange Commission, 100 F Street, NE, Washington, DC 20549-1090. The OMB has reviewed thiscollection of information under the clearance requirements of 44 U.S.C. § 3507. Item 1. Reports to Stockholders. (a)Include a copy of the report transmitted to stockholders pursuant to Rule 30e-1 under the Act (17 CFR 270.30e-1).The Report to Shareholders is attached herewith. The GDL FundAnnual Report — December31, 2024 (Y)our Portfolio Management Team Regina M. PitaroManaging DirectorBA, Fordham UniversityMA, Loyola University, ChicagoMBA, Columbia Business School Willis M. BruckerPortfolio ManagerBS, Boston College To Our Shareholders, For the year ended December31, 2024, the net asset value (NAV) total return of The GDL Fund was 5.6%, compared with a total returnof 5.3% for the ICE BofA 3 Month U.S. Treasury Bill Index. The total return for the Fund’s publicly traded shares was 5.9%. The Fund’s NAVper share was $10.26, while the price of the publicly traded shares closed at $8.02 on the New York Stock Exchange (NYSE). See page 3for additional performance information. Enclosed are the financial statements, including the schedule of investments, as of December31, 2024. Investment Objective (Unaudited) The Fund’s primary investment objective is to achieve absolute returns in various market conditions without excessive risk of capital.The Fund will seek to achieve its objective by investing primarily in merger arbitrage transactions and, to a lesser extent, in corporatereorganizations involving stubs, spin-offs, and liquidations. As permitted by regulations adopted by the Securities and Exchange Commission, paper copies of the Fund’s annual and semiannual shareholder reportswill no longer be sent by mail, unless you specifically request paper copies of the reports. Instead, the reports will be made available on the Fund’swebsite (www.gabelli.com), and you will be notified by mail each time a report is posted and provided with a website link to access the report. If youalready elected to receive shareholder reports electronically, you will not be affected by this change and you need not take any action. To elect to receiveall future reports on paper free of charge, please contact your financial intermediary, or, if you invest directly with the Fund, you may call 800-422-3554 orsend an email request to info@gabelli.com. Performance Discussion (Unaudited) During the first nine months of 2024, globally announced mergers and acquisitions (M&A) activity totaled $2.3 trillion, a 16% increasecompared to the same period in 2023. The third quarter saw a 14% increase in announced deal volume relative to the second quarter,totaling $784 billion. A total of 35,500 deals were announced globally year to date, with over 12,000 coming in the third quarter of the year.U.S. announced M&A has accounted for about half of total deal volumes, with deals across Europe increasing 30% year over year to $481billion, a two year high. The technology sector remained the most active, with $375 billion worth of new deals announced in the first three quarters of 2024,representing a 29% year-over-year increase. Energy and power and financials were the next most active, contributing 16% and 13%,respectively, to total deal volumes. Notable transactions in the quarter included Mars Company’s agreement to acquire snack food makerKellanova for $28.8 billion in an all-cash transaction and Verizon Communications arrangement to acquire Frontier Communications for $9.6billion. $847 billion worth of deals were agreed upon in the fourth quarter 2024, a sequential decline of 5% relative to the third quarter. Morethan 50,000 deals were announced on a global basis in 2024. Deal activity domestically totaled $1.4 trillion for the full year, a slight 5% riserelative to 2023 and the highest level in three years. Dealmaking within Europe