William Hill said it expected full-year operating profit to be lower than last year and that it was in advanced discussions to invest in gaming software company Openbet.
The firm expects 2016 operating profit to be in the range of £260m-£280m, compared with £291.4m last year.
The bookmaker attributed the lower profit expectations to regulatory changes in the gaming industry and unfavourable sporting results.
James Henderson, CEO of William Hill, said: “Today’s statement reflects the combined effect of our assessment of the impact of recent regulatory changes and unfavourable sporting results including the worst results at Cheltenham in our recent history.
“We are also experiencing softer UK growth as a consequence of acquiring lower value customers. While the rest of the Group is performing in line with our expectations, we continue to focus on improving Online’s performance so that we can, once again, outperform the market.”
Last month William Hill announced it will pay all its employees the national living wage.
William Hill employs over 12,500 people in its UK Retail business and while almost all are currently above the national minimum wage around 4,500 will benefit from the new national living wage.
From April 1, all businesses will be required to pay workers over the age of 25 atleast £7.20 an hour.
The voluntary application to 18-25s will benefit 2,000 staff in that age group, William Hill said.
William Hill is a major employer in Yorkshire, with more than a fifth of its global workforce in the region.
In Leeds alone William Hill employs 1,300 people, mainly in its technical and trading teams.