X0508 4 2025-12-04 0 0001288847 Five9, Inc. FIVN 0001846877 Mansharamani Leena C/O FIVE9, INC. 3001 BISHOP DR., STE. #350 SAN RAMON CA 94583 0 1 0 0 SVP, Chief Accounting Officer 1 Common Stock 2025-12-04 4 S 0 617 20.35 D 40905 D Common Stock 2025-12-04 4 S 0 1187 20.28 D 39718 D Common Stock 2025-12-04 4 S 0 1147 20.58 D 38571 D The sale reported on this form represents a Five9, Inc. mandated sale by the Reporting Person to cover tax withholding obligations in connection with the vesting and settlement of restricted stock units, and it does not represent a discretionary trade by the Reporting Person. The price reported in Column 4 is a weighted average price applied to the transaction by the broker for sales to cover taxes upon vesting of restricted stock units for all employees of Five9, Inc., including the Reporting Person, on the date such sales occurred. 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. The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on December 10, 2024. 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 $20.18 to $20.42, 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 $20.42 to $20.73, 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 2025-12-05