ACAS American Capital, Ltd.

Filed by Ares Capital Corporation

pursuant to Rule 425 under the Securities Act of 1933

and deemed filed under Rule 14a-12 of the Securities Exchange Act of 1934

Subject Company: American Capital, Ltd.

Commission File No. 814-00149

MERGER PROPOSED—YOUR VOTE IS VERY IMPORTANT

PLEASE VOTE THE ENCLOSED PROXY CARD TODAY

November 25, 2016

Dear Stockholder:

According to our latest records, we have not yet received your voting instructions for the Special Meeting of Stockholders of Ares Capital Corporation to be held on Thursday, December 15, 2016. Your vote is extremely important, no matter how many shares you hold.

For the reasons set forth in the joint proxy statement, dated October 18, 2016, your Board of Directors recommends that you vote “FOR” proposals 1, 2 and 3. Please authorize your proxy via the internet at www.proxyvote.com as soon as possible or alternatively, please authorize your proxy by phone at (800) 690-6903 or by marking, signing dating, and returning the enclosed proxy card.

Please understand that it is critical that we receive your vote so that we may complete the business of the Special Meeting of Stockholders without delay.

If you need assistance voting your shares, please call D.F. King toll-free at (800) 967-7635 or collect at (212) 269-5550. On behalf of your Board of Directors, thank you for your cooperation and continued support.

Sincerely,

Disclaimer

No Offer or Solicitation

The information in this communication is for informational purposes only and shall not constitute an offer to sell or the solicitation of an offer to sell or the solicitation of an offer to buy any securities or the solicitation of any vote or approval in any jurisdiction pursuant to or in connection with the proposed transaction or otherwise, nor shall there be any sale, issuance or transfer of securities in any jurisdiction in contravention of applicable law. No offer of securities shall be made except by means of a prospectus meeting the requirements of Section 10 of the Securities Act of 1933, as amended.

Additional Information and Where to Find It

In connection with the proposed transaction, Ares Capital has filed with the Securities and Exchange Commission (the “SEC”) a registration statement on Form N-14 (the “Registration Statement”) that includes a joint proxy statement of Ares Capital and American Capital (the “Joint Proxy Statement”) and that constitutes a prospectus of Ares Capital.  The Joint Proxy Statement and Registration Statement, as applicable, have been mailed or otherwise delivered to stockholders as required by applicable law. INVESTORS AND SECURITY HOLDERS ARE URGED TO READ THE JOINT PROXY STATEMENT AND THE REGISTRATION STATEMENT, AS WELL AS ANY AMENDMENTS OR SUPPLEMENTS TO THESE DOCUMENTS, CAREFULLY AND IN THEIR ENTIRETY BECAUSE THEY CONTAIN IMPORTANT INFORMATION ABOUT AMERICAN CAPITAL, ARES CAPITAL, THE PROPOSED TRANSACTION AND RELATED MATTERS.  Investors and security holders will be able to obtain the Joint Proxy Statement, the Registration Statement and other documents filed with the SEC by American Capital and Ares Capital, free of charge, from the SEC’s website at www.sec.gov and from either American Capital’s or Ares Capital’s websites at www.americancapital.com or at www.arescapitalcorp.com. Investors and security holders may also obtain free copies of the Joint Proxy Statement, the Registration Statement and other documents filed with the SEC from American Capital by contacting American Capital’s Investor Relations Department at 1-301-951-5917 or from Ares Capital by contacting Ares Capital’s Investor Relations Department at 1-888-818-5298.

Participants in the Solicitation

American Capital, Ares Capital and their respective directors, executive officers, other members of their management and employees may be deemed to be participants in the solicitation of proxies in connection with the proposed transaction. Information regarding the persons who may, under the rules of the SEC, be considered participants in the solicitation of the Ares Capital and American Capital stockholders in connection with the proposed transaction, and their direct or indirect interests, by security holdings or otherwise, is set forth in the Joint Proxy Statement and Registration Statement filed with the SEC. These documents may be obtained free of charge from the sources indicated above.

Cautionary Statement Regarding Forward-Looking Statements

This communication contains “forward-looking” statements as that term is defined in Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended by the Private Securities Litigation Reform Act of 1995, including statements regarding the proposed transaction between American Capital and Ares Capital pursuant to a merger between American Capital and Ares Capital. All statements, other than historical facts, including statements regarding the expected timing of the closing of the proposed transaction; the ability of the parties to complete the proposed transaction considering the various closing conditions; the expected benefits of the proposed transaction such as improved operations, enhanced revenues and cash flow, growth potential, market profile and financial strength; the competitive ability and position of the combined company following completion of the proposed transaction; and any assumptions underlying any of the foregoing, are forward-looking statements. Forward-looking statements concern future circumstances and results and other statements that are not historical facts and are sometimes identified by the words “may,” “will,” “should,” “potential,” “intend,” “expect,” “endeavor,” “seek,” “anticipate,” “estimate,” “overestimate,” “underestimate,” “believe,” “could,” “project,” “predict,” “continue,” “target” or other similar words or expressions. Forward-looking statements are based upon current plans, estimates and expectations that are subject to risks, uncertainties and assumptions. Should one or more of these risks or uncertainties materialize, or should underlying assumptions prove incorrect, actual results may vary materially from those indicated or anticipated by such forward-looking statements. The inclusion of such statements should not be regarded as a representation that such plans, estimates or expectations will be achieved. Important factors that could cause actual results to differ materially from such plans, estimates or expectations include, among others, (1) that one or more closing conditions to the transaction may not be satisfied or waived, on a timely basis or otherwise, including that a governmental entity may prohibit, delay or refuse to grant approval for the consummation of the proposed transaction, may require conditions, limitations or restrictions in connection with such approvals or that the required approval by the stockholders of each of American Capital and Ares Capital may not be obtained; (2) the risk that the mergers or other transactions contemplated by the ARCC/ACAS merger agreement may not be completed in the time frame expected by American Capital and Ares Capital, or at all; (3) unexpected costs, charges or expenses resulting from the proposed transaction; (4) uncertainty of the expected financial performance of the combined company following completion of the proposed transaction; (5) failure to realize the anticipated benefits of the proposed transaction, including as a result of delay in completing the proposed transaction or integrating the businesses of American Capital and Ares Capital; (6) the ability of the combined company to implement its business strategy; (7) difficulties and delays in achieving synergies and cost savings of the combined company; (8) inability to retain and hire key personnel; (9) the occurrence of any event that could give rise to termination of the ARCC/ACAS merger agreement; (10) the risk that stockholder litigation in connection with the proposed transaction may affect the timing or occurrence of the contemplated merger or result in significant costs of defense, indemnification and liability; (11) evolving legal, regulatory and tax regimes; (12) changes in laws or regulations or interpretations of current laws and regulations that would impact Ares Capital’s classification as a business development company; (13) changes in general economic and/or industry specific conditions; and (14) other risk factors as detailed from time to time in American Capital’s and Ares Capital’s reports filed with the SEC, including American Capital’s and Ares Capital’s respective annual reports on Form 10-K for the year ended December 31, 2015, periodic quarterly reports on Form 10-Q, periodic current reports on Form 8-K, the Joint Proxy Statement, the Registration Statement and other documents filed with the SEC.

Any forward-looking statements speak only as of the date of this communication. Neither American Capital nor Ares Capital undertakes any obligation to update any forward-looking statements, whether as a result of new information or development, future events or otherwise, except as required by law. Readers are cautioned not to place undue reliance on any of these forward-looking statements.