X0306 4 2017-08-28 0 0001609989 Blue Buffalo Pet Products, Inc. BUFF 0001647806 Nathenson Michael C/O BLUE BUFFALO PET PRODUCTS, INC. 11 RIVER ROAD WILTON CT 06897 0 1 0 0 EVP, CFO and Treasurer Common Stock 2017-08-28 4 M 0 50000 5.60 A 50000 D Common Stock 2017-08-28 4 S 0 50000 25.77 D 0 D Stock Option (Right to Buy) 5.60 2017-08-28 4 M 0 50000 0.00 D 2022-12-18 Common Stock 50000 589542 D The sales reported on this Form 4 were effected pursuant to a Rule 10b5-1 trading plan. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $25.64 to $26.10, inclusive. The Reporting Person undertakes to provide to the issuer, any security holder of the issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth above. Reflects an initial option grant with respect to 803,300 shares that vests in five equal annual installments beginning on December 18, 2013. /s/ Karen M. McCarthy, as Attorney-in-Fact 2017-08-29