144 0002080340 XXXXXXXX LIVE 0001288847 Five9, Inc. 001-36383 3001 Bishop Dr. Ste 350 San Ramon CA 94583 9252012000 Matthew Tuckness Officer Common Morgan Stanley Smith Barney LLC

Executive Financial Services 1 New York Plaza 8th Floor New York NY 10004

5324 93010.28 76550422 03/04/2026 Nasdaq Common 03/03/2026 RSU Issuer N 5324 03/03/2026 Not Applicable N Matthew Tuckness

3001 Bishop Dr. Suite 350 San Ramon CA 94583

Common 12/04/2025 5255 106939.25 The sale reported on this Form 144 represents an Issuer 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. 03/03/2026 Matthew Tuckness