X0306 4 2019-06-04 0 0001370053 ANAPTYSBIO INC ANAB 0001654500 Londei Marco C/O ANAPTYSBIO, INC. 10421 PACIFIC CENTER COURT, SUITE 200 SAN DIEGO CA 92121 0 1 0 0 Chief Medical Officer Common Stock 2019-06-04 4 M 0 10060 0.70 A 32437 D Common Stock 2019-06-04 4 S 0 6009 72.4511 D 26428 D Common Stock 2019-06-04 4 S 0 2048 73.4296 D 24380 D Common Stock 2019-06-04 4 S 0 2003 74.4978 D 22377 D Employee Stock Option (Right to Buy) 0.70 2019-06-04 4 M 0 10060 0.00 D 2024-10-27 Common Stock 10060 0 D The transactions reported on this Form 4 were effected pursuant to a 10b5-1 trading plan adopted by the reporting person. The reported price in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $72.00 to $72.99 per share, 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 written request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote. The reported price in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $73.04 to $73.98 per share, 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 written request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote. The reported price in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $74.085 to $74.78 per share, 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 written request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote. The stock option vested and became exercisable as to 25% of the shares subject to the option on October 24, 2015, and thereafter vests as to 1/48th of the shares in equal monthly installments, until such time as the option is 100% vested, subject to the continuing employment of the Reporting Person on each vesting date. The Reporting Person also holds (i) additional options to purchase up to an aggregate of 224,148 shares of common stock, which options vest according to their terms, and (ii) 22,377 shares of common stock held directly. /s/Eric Loumeau, attorney-in-fact 2019-06-05