X0303 4 2010-10-13 0001111928 IPG PHOTONICS CORP IPGP 0001130421 GAPONTSEV VALENTIN P C/O IPG PHOTONICS CORPORATION 50 OLD WEBSTER ROAD OXFORD MA 01540 1 1 1 0 CEO & Chairman of the Board Common Stock 2010-10-13 4 S 0 130537 21.37 D 7873465 I Through IP Fibre Devices (UK) Ltd. Common Stock 2010-10-14 4 S 0 52563 21.70 D 7820902 I Through IP Fibre Devices (UK) Ltd. Common Stock 2010-10-15 4 S 0 4800 21.82 D 7816102 I Through IP Fibre Devices (UK) Ltd. The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on September 13, 2010. The reported transaction involved sales transactions from $21.00 to $21.70 per share. The Reporting Person undertakes to provide upon request by the SEC staff, the Issuer or a security holder of the Issuer information regarding the number of shares sold at each separate price. The reported transaction involved sales transactions from $21.60 to $21.80 per share. The Reporting Person undertakes to provide upon request by the SEC staff, the Issuer or a security holder of the Issuer information regarding the number of shares sold at each separate price. The reported transaction involved sales transactions from $21.80 to $21.85 per share. The Reporting Person undertakes to provide upon request by the SEC staff, the Issuer or a security holder of the Issuer information regarding the number of shares sold at each separate price. The reporting person is the managing director of IP Fibre Devices (UK) Ltd. and has voting and investment power with respect to the shares held of record by IP Fibre Devices (UK) Ltd. 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 the reported shares for purposes of Section 16 of the Securities Exchange Act of 1934, as amended, or for any other purpose. Angelo P. Lopresti, Attorney-at-law 2010-10-15