Michael Porter, Director at PTC, holds 699.45K shares in Merrimack Pharmaceuticals (Ticker: MACK), holds 231.60K shares in PTC (Ticker: PTC), holds 22.20K shares in Scotts Miracle-Gro Company (Ticker: SMG). Most recently, Michael Porter Bought ― shares of Merrimack Pharmaceuticals on Mar 13, 2017 for an estimated value of 228.65K.