X0202 4 2005-05-06 0 0001103345 BEACON POWER CORP BCON 0000927752 PEARL FRANK H C/O PERSEUS CAPITAL, L.L.C. 2099 PENNSYLVANIA AVENUE, NW, SUITE 900 WASHINGTON DC 20006 0 0 1 0 Stock Option (right to buy) 0.87 2005-05-06 2005-05-06 4 J 0 29168 A 2005-05-30 2015-05-29 Common Stock 29168 29168 I Through Perseus Capital, L.L.C. Stock Option (right to buy) 0.465 2005-05-06 2005-05-06 4 J 0 29168 D 2004-12-30 2014-12-08 Common Stock 29168 20832 I Through Perseus Capital, L.L.C. A Stock Option granted to Mr. John C. Fox, a member of the Issuer's board of directors, and held for the benefit of Perseus Capital, L.L.C., of which Mr. Fox is employed as a Managing Director. Mr. Fox disclaims beneficial ownership of the reported securities, except to the extent of his pecuniary interest therein, if any. Vests in seven installments on the 30th of each month beginning May 30, 2005. Stock Option grant. The Reporting Person is the Chairman of Perseus, L.L.C., which through certain subsidiary entities controls Perseus Capital, L.L.C., which beneficially owns the reported securities. The Reporting Person disclaims beneficial ownership of the reported securities, except to the extent of his pecuniary interest therein. Cancellation of the remainder of a stock option previously granted to Mr. Philip J. Deutch, upon Mr. Deutch's resignation from the Issuer's board of directors effective as of May 06, 2005. The reported securities had been held by Mr. Deutch for the benefit of Perseus Capital, L.L.C., of which Mr. Deutch had been employed as a Managing Director. Mr. Deutch disclaimed beneficial ownership of the reported securities, except to the extent of his pecuniary interest therein, if any. By: Rodd Macklin, Attorney-in-Fact 2005-05-09