Security	Date	Code	Shares	Price	A/D	Owned after	D/I	Nature of ownership
Common Shares^F2,F3	Apr 24, 2018	S	20,071	$51.00	D	1,519,505	I	See footnote
Common Shares^F2,F5	Apr 24, 2018	S	589	$50.60	D	44,582	I	See footnote
Common Shares^F2,F7	Apr 24, 2018	S	653	$51.00	D	49,419	I	See footnote
Common Shares^F2,F9	Apr 24, 2018	S	1,528	$51.00	D	115,645	I	See footnote

Table II — derivative securities

No Table II lines on this filing.

Explanation of responses

F1The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by Versant Venture Capital V, L.P. ("VVC V").
F2The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $50.00 to $51.59 per share, inclusive. The reporting person undertakes to provide to CRISPR Therapeutics AG, any security holder of CRISPR Therapeutics AG, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the ranges set forth herein.
F3These securities are held of record by VVC V. Versant Ventures V, LLC ("VV V") is the sole general partner of VVC V and may be deemed to have voting and investment power over the securities held by VVC V and as a result may be deemed to have beneficial ownership over such securities, however, VV V disclaims beneficial ownership of the securities held by VVC V, except to the extent of its pecuniary interest therein.
F4The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by Versant Affiliates Fund V, L.P. ("VAF V").
F5These securities are held of record by VAF V. VV V is the sole general partner of VAF V and may be deemed to have voting and investment power over the securities held by VAF V and as a result may be deemed to have beneficial ownership over such securities, however, VV V disclaims beneficial ownership of the securities held by VAF V, except to the extent of its pecuniary interest therein.
F6The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by Versant Ophthalmic Affiliates Fund I, L.P. ("VOA").
F7These securities are held of record by VOA. VV V is the sole general partner of VOA and may be deemed to have voting and investment power over the securities held by VOA and as a result may be deemed to have beneficial ownership over such securities, however, VV V disclaims beneficial ownership of the securities held by VOA, except to the extent of its pecuniary interest therein.
F8The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by Versant Venture Capital V (Canada), L.P. ("VVC CAN").
F9These securities are held of record by VVC CAN. Versant Ventures V GP-GP (Canada), Inc. ("VV V CAN GP") is the sole general partner of Versant Ventures V (Canada), L.P. ("VV V CAN") and VV V CAN is the sole general partner of VVC CAN. VV V CAN GP and VV V CAN may be deemed to have voting and investment power over the securities held by VVC CAN and as a result may be deemed to have beneficial ownership over such securities, however, VV V CAN GP and VV V CAN each disclaim beneficial ownership of the securities held by VVC CAN, except to the extent of their pecuniary interests therein.