X0202 4/A 2005-04-22 2005-05-26 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 1 0 1 0 Common Stock 2005-04-22 4 A 0 1666667 0.84 A 9169018 I Through Perseus 2000 Expansion, L.L.C. and Perseus Capital, L.L.C. Obligation to Purchase 0.84 2005-04-22 4 A 0 1 0.00 A 2005-04-22 2005-09-30 Common Stock 1785714 1 I Through Perseus 2000 Expansion, L.L.C. Warrant 1.008 2005-04-22 4 A 0 800000 0.00 A 2005-04-22 2010-05-24 Common Stock 800000 800000 I Through Perseus 2000 Expansion, L.L.C. Warrant 2.25 2005-04-22 4 A 0 1333333 100000.00 A 2005-04-22 2007-05-23 Common Stock 1333333 1333333 I Through Perseus Capital, L.L.C. Acquired pursuant to an Investment Agreement, dated as of April 22, 2005, by and among the Issuer, Perseus 2000 Expansion, L.L.C. and Perseus Capital, L.L.C., pursuant to which Perseus 2000 Expansion, L.L.C. agreed to acquire the securities reported by this filing on a date to be specified in the future, and provided the Issuer with the additional right to sell to the Reporting Person shares of the Issuer's common stock at the Issuer's sole option. The Reporting Person disclaims beneficial ownership of the reported securities, except to the extent of his pecuniary interest therein. The Reporting Person controls entities that have director representation on the Issuer's board of directors and which entities are deemed to be directors thereof by deputization. This disclosure item references a Warrant, initially dated May 23, 2000, exercisable for 1,333,333 shares of the Issuer's common stock. Pursuant to an Investment Agreement among the Issuer, Perseus Capital, L.L.C. and Perseus 2000 Expansion, L.L.C., dated as of April 22, 2005 and previously disclosed to and filed with the Securities Ecxhange Commission, Perseus Capital, L.L.C. agreed to pay to the Issuer $100,000 in exchange for an extension of the expiration of the date of the Warrant from May 23, 2005 to May 23, 2007. The payment for this extension was made on May 24, 2005. By: Rodd Macklin, Attorney in Fact 2005-09-02