X0609 4 2026-10-16 0 0001517413 Fastly, Inc. FSLY 0002074428 Compton Charles Lacey III false C/O FASTLY, INC. 475 BRANNAN STREET, SUITE 300 SAN FRANCISCO CA 94107 1 1 0 0 CEO 1 Class A Common Stock 2026-10-16 4 S 0 11433 24.90 D 840516 D Class A Common Stock 2026-10-19 4 S 0 9016 23.08 D 831500 D Shares sold to satisfy tax obligations in connection with the vesting of previously granted Restricted Stock Units. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $24.67 to $24.90, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the SEC, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in footnotes (2) and (4) to this Form 4. The sale was effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on May 11, 2026. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $22.79 to $23.43, inclusive. /s/ Tara Seracka, Attorney-in-Fact 2026-10-20