X0303 4 2011-05-20 0 0001167178 A123 SYSTEMS, INC. AONE 0001472633 Cole Andrew C/O A123 SYSTEMS, INC. 200 WEST STREET WALTHAM MA 02451 0 1 0 0 VP of HR and Organiz. Develop. Common Stock 2011-05-20 4 A 0 40000 0.00 A 59783 D Common Stock 2011-05-23 4 S 0 4945 5.5247 D 54838 D Stock Option (right to buy) 5.66 2011-05-20 4 A 0 50000 0.00 A 2021-05-20 Common Stock 50000 50000 D Restricted stock units ("RSUs"). Upon vesting thereof, the Reporting Person is entitled to receive one (1) share of common stock for each one (1) RSU. 25% of the RSUs will vest on May 20, 2012, and 6.25% of the total number of RSUs will vest at the end of each three-month period thereafter, so that 100% of the RSUs will be fully vested on May 20, 2015. Includes 54,838 RSUs. The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan. These transactions were executed in multiple trades in prices ranging from $5.50 to $5.55. The price reported in Column 4 above reflects the weighted average sale price. The Reporting Person hereby undertakes to provide to the SEC staff, the Issuer, or a security holder of the Issuer, upon request, full information regarding the number of shares sold at each respective price within the range set forth in this footnote. Option vests with respect to 25% of the shares subject thereto on May 20, 2012, and 6.25% of the total shares subject to the option will vest at the end of each three-month period thereafter, such that the option will be fully vested and exercisable on May 20, 2015. /s/ Eric J. Pyenson, Attorney-in-Fact for Andrew Cole 2011-05-24