April 30, 2010

Exhibit 10.1

April 30, 2010

American Capital, Ltd.

0 Xxxxxxxx Xxxxx Xxxxxx

00xx Xxxxx

Xxxxxxxx, XX 00000

Attn: Compliance Officer

Weil, Gotshal & Xxxxxx LLP

000 Xxxxx Xxxxxx

Xxx Xxxx, XX 00000

Attn:     Xxxxxxxxxxx Xxxxx

     Xxxxxxx Xxxxxxxxx

     Xxxxx Xxxxxxxxx

Ladies and Gentlemen:

Reference is made to the Lock Up Agreement, dated as of November 20, 2009 (the “Lock Up”), by and among American Capital, Ltd., a Delaware corporation (the “Company”), and each of the creditors party thereto (the “Consenting Creditors”). Capitalized terms not otherwise defined herein shall have the meanings ascribed to such terms in the Lock Up. This letter is to confirm that the Company and the Administrative Agent hereby agree to extend the date of “May 31, 2010” to “June 30, 2010” in both Section 4(ii)(A)(1) and Section 4(ii)(A)(2) of the Lock Up in accordance with the terms therein.

If the above correctly reflects our understanding with respect to the foregoing matters, please so confirm by signing the enclosed copy of this letter.

Very truly yours,
XXXXX FARGO BANK, N.A., as Administrative Agent
By:		/s/ Xxxx Xxxxxxx
Name: Title:		Xxxx Xxxxxxx Director

Agreed to and accepted as of the date first set forth above:

AMERICAN CAPITAL, LTD.
By:		/s/ Xxxxxx X. Xxxx
Name: Title:		Xxxxxx X. Xxxx Executive Vice President, CCO, General Counsel and Secretary