X0508 4 2023-10-18 0001042074 CymaBay Therapeutics, Inc. CBAY 0001588862 McWherter Charles C/O CYMABAY THERAPEUTICS, INC. 7575 GATEWAY BLVD., SUITE 110 NEWARK CA 94560 0 1 0 0 President of R&D 0 Common Stock 2023-10-18 4 M 0 21743 5.00 A 36743 D Common Stock 2023-10-18 4 S 0 21743 14.0708 D 15000 D Employee Stock Option (right to buy) 5.00 2023-10-18 4 M 0 10401 0 D 2023-10-30 Common Stock 10401 0 D Employee Stock Option (right to buy) 5.00 2023-10-18 4 M 0 708 0 D 2023-12-22 Common Stock 708 1412 D Employee Stock Option (right to buy) 5.00 2023-10-18 4 M 0 236 0 D 2023-12-22 Common Stock 236 470 D Employee Stock Option (right to buy) 5.00 2023-10-18 4 M 0 3892 0 D 2023-12-22 Common Stock 3892 7782 D Employee Stock Option (right to buy) 5.00 2023-10-18 4 M 0 6506 0 D 2024-01-05 Common Stock 6506 13010 D The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan entered into on February 24, 2023. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $13.91 to $14.21, inclusive. The reporting person undertakes to provide to CymaBay Therapeutics, Inc., any security holder of CymaBay Therapeutics, Inc., 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 in this footnote. The option vested as to 1/3 of the underlying shares on October 31, 2013 and the remaining 2/3 of the underlying shares vested ratably on a monthly basis over the 48 months thereafter. The original option vested as to 1/4 of the underlying shares on July 23, 2008 and the remaining 3/4 of the underlying shares vested ratably on a monthly basis over the 36 months thereafter. The original option vested as to 1/48 of the underlying shares monthly from October 15, 2009. The option vested in full on December 23, 2015. The option vested as to 1/3 of the underlying shares on January 6, 2014 and the remaining 2/3 of the underlying shares vested ratably on a monthly basis over the 48 months thereafter. /s/ Paul Quinlan, as attorney-in-fact for Charles McWherter 2023-10-18