Up to 650 jobs are under threat across Britain and Ireland as a result of the merger of Paddy Power and Betfair which was completed in February.
Up to 300 jobs will be cut in Ireland with another 350 positions threatened in the UK as the company restructures and removes duplication of roles within the two businesses, although it is hoped that some staff can be redeployed.
Staff were told the news on Monday with areas affected including legal, HR, finance, technology, trading and risk.
The company will have staff in single offices in both countries. Staff in Paddy Power's office in London will move to Hammersmith while the Betfair site in Stevenage, which was home to a range of departments including customer services, social media, monitoring and settling of betting markets and housed 250 staff, will close.