X0306 4 2015-10-28 1 0000899723 OM GROUP INC OMG 0001467341 Knowles David B FLATS EAST BANK BUILDING, 950 MAIN AVENUE, SUITE 1300 CLEVELAND OH 44113 0 1 0 0 President and COO Common Stock 2015-10-28 4 D 0 30700 34.00 D 77402 D Common Stock 2015-10-28 4 D 0 25700 34.00 D 51702 D Common Stock 2015-10-28 4 D 0 14800 34.00 D 36902 D Common Stock 2015-10-28 4 D 0 36400 34.00 D 502 D Common Stock 2015-10-28 4 D 0 502 34.00 D 0 D Employee Stock Options (right to buy) 22.47 2015-10-28 4 D 0 14000 11.53 D 2023-04-08 Common Stock 14000 0 D Employee Stock Options (right to buy) 22.47 2015-10-28 4 D 0 36000 11.53 D 2023-04-08 Common Stock 36000 0 D Employee Stock Options (right to buy) 32.24 2015-10-28 4 D 0 31700 1.76 D 2024-02-11 Common Stock 31700 0 D Employee Stock Options (right to buy) 29.04 2015-10-28 4 D 0 46400 4.96 D 2025-02-10 Common Stock 46400 0 D Half of these performance units were disposed of pursuant to a merger agreement, dated May 31, 2015, by and among Duke Acquisition Holdings, LLC, Duke Acquisition, Inc., MacDermid Americas Acquisitions, Inc., and the Issuer (the "Merger Agreement") in exchange for the right to receive $34.00 in cash per performance unit, representing payout for the applicable performance share award at target performance level, plus any earned cash dividend equivalents, with the remaining performance units forfeited back to the Issuer for no consideration. Includes 502 dividend equivalents acquired on outstanding performance units awards and time-based restricted stock units awards through exempt dividend equivalent features. Performance units disposed of pursuant to the Merger Agreement in exchange for the right to receive $34.00 in cash per performance unit, representing payout for the applicable performance share award at target performance level. Time-based restricted stock units disposed of pursuant to the Merger Agreement in exchange for the right to receive $34.00 in cash per unit. Dividend equivalents on outstanding performance units awards and time-based restricted stock units awards disposed of pursuant to the Merger Agreement in exchange for the right to receive $34.00 in cash per dividend equivalent. These options vested or were to vest in three equal installments on April 8, 2014, 2015 and 2016. These options vested or were to vest in three equal installments on February 11, 2015, 2016, and 2017. These options were to vest in three equal installments on February 10, 2016, 2017 and 2018. Disposed of pursuant to the Merger Agreement in exchange for a cash payment approximately equal to the difference (if positive) between $34.00 and the exercise price of the stock option multiplied by the number of outstanding shares (both vested and unvested) subject to the stock option. /s/ Valerie Gentile Sachs, as Attorney-In-Fact 2015-10-30