X0303 4 2008-08-11 0 0001157601 SYNTA PHARMACEUTICALS CORP SNTA 0001325713 Kovner Bruce C/O CAXTON ASSOCIATES 500 PARK AVENUE NEW YORK NY 10022 1 0 1 0 Common Stock 2008-08-11 4 P 0 25100 7.1502 A 932567 D Common Stock 2008-08-12 4 P 0 1300 7.3692 A 933867 D Common Stock 7761716 I By CxSynta LLC This transaction was executed in multiple trades at prices ranging from $6.99 to $7.32 per share. The price reported above reflects the weighted average purchase price. The Reporting Person hereby undertakes to provide upon request to the SEC staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected. This transaction was executed in multiple trades at prices ranging from $7.34 to $7.49 per share. The price reported above reflects the weighted average purchase price. The Reporting Person hereby undertakes to provide upon request to the SEC staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected. These shares are owned directly by CxSynta LLC and indirectly by the Reporting Person as Chairman of Caxton Corporation, the managing member of CxSynta LLC. The Reporting Person disclaims beneficial ownership of these securities except to the extent of his pecuniary interest therein, and the inclusion of these shares in this report shall not be deemed an admission of the beneficial ownership of all of the reported shares for purposes of Section 16 or for any other purpose. /s/ Scott B. Bernstein, Attorney-in-Fact 2008-08-13