Item 3.03 Material Modification to Rights of Security Holders.

On December 21, 2012, Active Power, Inc. (the "Company") filed with the Secretary of State of the State of Delaware a Certificate of Amendment of the Company's Restated Certificate of Incorporation (the "Certificate of Amendment") to effect a reverse stock split of the Company's outstanding Common Stock at a reverse split ratio of five-for-one (the "Reverse Stock Split"), reduce the total number of shares of Common Stock that the Company is authorized to issue to 30,000,000, and reduce the total number of shares of Preferred Stock that the Company is authorized to issue to 2,000,000. The par value per share of the common stock before and after the split is $0.001. A copy of the Certificate of Amendment is attached as Exhibit 3.1 hereto and incorporated herein by reference.

The Reverse Stock Split became effective as of 5:00 a.m. EST on December 21, 2012.

Under the terms of the Company's equity plans,, a proportionate adjustment was made to the per share exercise price and the number of shares issuable upon the exercise of all outstanding options to purchase shares of the Company's common stock, the number of shares issuable upon the vesting of outstanding restricted stock units and the number of shares reserved for issuance pursuant to such plans.

No scrip or fractional shares will be issued as a result of the Reverse Stock Split. Instead, the Company will pay, in cash, the value of any fractional share interest arising from the Reverse Stock Split.

The new CUSIP number for the Company's common stock following the reverse stock split is 00504W 308.

Item 9.01 Financial Statements and Exhibits.

(d) Exhibits

3.1 Certificate of Amendment to Restated Certificate of Incorporation

---