X0609 4 2026-09-03 0 0001288847 Five9, Inc. FIVN 0001846877 Mansharamani Leena false C/O FIVE9, INC. 3001 BISHOP DR., STE. #350 SAN RAMON CA 94583 0 1 0 0 SVP, Chief Accounting Officer 1 Common Stock 2026-09-03 4 S 0 2558 34.19 D 56476 D Common Stock 2026-09-03 4 S 0 100 35.05 D 56376 D Common Stock 2026-09-04 4 S 0 2505 33.32 D 53871 D Common Stock 2026-09-04 4 S 0 201 33.71 D 53670 D Common Stock 2026-09-08 4 S 0 1253 31.53 D 52417 D The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on June 4, 2026. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $33.98 to $34.57, inclusive. The reporting person undertakes to provide Five9, Inc., any security holder of Five9, 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 ranges set forth in this footnote. Includes 1,336 shares acquired under the Five9, Inc. Employee Stock Purchase Plan on May 15, 2026. The reported sales were to cover taxes upon the vesting of 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 $32.65 to $33.65, inclusive. The reporting person undertakes to provide Five9, Inc., any security holder of Five9, 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 ranges set forth in this footnote. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $33.69 to $33.75, inclusive. The reporting person undertakes to provide Five9, Inc., any security holder of Five9, 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 ranges set forth in this footnote. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $31.17 to $31.92, inclusive. The reporting person undertakes to provide Five9, Inc., any security holder of Five9, 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 ranges set forth in this footnote. /s/ Tiffany Meriweather, Attorney in Fact 2026-09-08