X0303 4 2010-08-19 0 0001333170 NxStage Medical, Inc. NXTM 0001382096 Brown Robert S. C/O NXSTAGE MEDICAL, INC. 439 SOUTH UNION STREET, 5TH FLOOR LAWRENCE MA 01843 0 1 0 0 Sr. Vice President, CFO Common Stock 2010-08-19 4 M 0 2000 2.11 A 74784 D Common Stock 2010-08-19 4 S 0 2000 16.61 D 72784 D Common Stock 2010-08-19 4 S 0 3000 16.61 D 69784 D Stock Option (right to buy) 2.11 2010-08-19 4 M 0 2000 0.00 D 2009-04-05 2016-03-04 Common Stock 2000 66000 D This sale was effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on March 12, 2010. The option was granted March 5, 2009 and vests over three years in equal monthly installments. /s/ Winifred L. Swan, attorney-in-fact 2010-08-19