X0202 4 2005-12-28 0001018399 ENTERPRISE BANCORP INC /MA/ EBTC 0001282782 ARMSTRONG WALLY C/O ENTERPRISE BANCORP INC 222 MERRIMACK STREET LOWELL MA 01852 1 0 0 0 Common Stock 2005-12-28 4 S 0 .7083 33.26 D 76476.2083 D Common Stock 2006-01-26 4 S 0 3500 30.52 D 72976.2083 D Common Stock 2006-06-09 4 S 0 497 32.0159 D 72483.8735 D Common Stock 2006-06-12 4 S 0 100 32.25 D 72383.8735 D Common Stock 2006-06-12 4 S 0 900 32.00 D 71483.8735 D Common Stock 2006-11-02 4 S 0 3000 15.4783 D 139972.4196 D Common Stock 2006-11-03 4 S 0 1000 15.49 D 138972.4196 D Includes 219.5935 shares of Common Stock acquired under the EBTC dividend reinvestment plan. Includes 4.6652 shares of Common Stock acquired under the EBTC dividend reinvestment plan. Includes 4.6726 shares of Common Stock acquired under the EBTC dividend reinvestment plan. Reflects additional 71,483.8735 shares of EBTC stock which reporting person received on June 30, 2006 when the stock of EBTC split 2-for-1. /s/ George L. Duncan as attorney-in-fact 2006-11-06