X0306 4 2013-06-21 0 0001157601 SYNTA PHARMACEUTICALS CORP SNTA 0001325713 Kovner Bruce C/O CAXTON CORPORATION 731 ALEXANDER ROAD, BLDG 2 PRINCETON NJ 08540 1 0 1 0 Common Stock 2013-06-24 4 P 0 200000 4.4296 A 2450000 I By Kovner 2012 Family Trust B Common Stock 2013-06-21 4 P 0 50000 4.2304 A 2250000 I By Kovner 2012 Family Trust B Common Stock 6170330 D Common Stock 125000 I By Kovner 2011-A Investment Trust Common Stock 125000 I By Kovner 2011-B Investment Trust Common Stock 125000 I By Kovner 2011-C Investment Trust Common Stock 125000 I By Kovner 2011-D Investment Trust Common Stock 475000 I By Kovner 2012-A Synta Investment Trust Common Stock 475000 I By Kovner 2012-B Synta Investment Trust Common Stock 475000 I By Kovner 2012-C Synta Investment Trust Common Stock 475000 I By Kovner 2012-D Synta Investment Trust Common Stock 4199803 I By KFO Holdings LLC Common Stock 7761716 I By CxSynta LLC The shares were purchased in multiple transactions at prices ranging from $4.25 to $4.52 per share. The price reported above is the weighted average purchase price. The Reporting Person hereby undertakes to provide upon request to the staff of the SEC, the Issuer or a security holder of the Issuer, full information regarding the number of shares purchased at each separate price within the range set forth above. The shares were purchased in multiple transactions at prices ranging from $3.92 to $4.35 per share. The price reported above is the weighted average purchase price. The Reporting Person hereby undertakes to provide upon request to the staff of the SEC, the Issuer or a security holder of the Issuer, full information regarding the number of shares purchased at each separate price within the range set forth above. These shares are owned directly by KFO Holdings LLC ("KFO") and indirectly by the Reporting Person as the sole member of KFO. These shares are owned directly by CxSynta LLC and indirectly by the Reporting Person as chairman and sole shareholder of Caxton Corporation, the managing member of CxSynta LLC. The Reporting Person disclaims beneficial ownership of these shares 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/ Heath N. Weisberg, as Attorney-in-Fact for Bruce Kovner 2013-06-25