Flutter says move in budget will affect underlying earnings by about $320m in 2025-26 and $540m in 2026-27.
The Paddy Power and Betfair owner, Flutter Entertainment, has warned the budget move to increase UK gambling taxes will hit its annual profits by $860m (£650m) over the next two years.
The chancellor, Rachel Reeves, announced on Wednesday that remote online gaming duty would rise from 21% to 40%, while online sports betting – excluding horse racing – would increase from 15% to 25%.