William Hill's latest market update showed 874,189,537 of its shares had been purchased by Fred and Peter Done's company, for an undisclosed fee.
When asked for the reasons behind the acquisition, a source close to Betfred told Gambling Insider: "He (Fred Done) bought Hill’s shares because they are massively undervalued and when it comes to the US they are the front runners."
Last month, William Hill reported a 2% year-on-year decrease in its full-year net revenue for 2019, to £1.58bn ($2.05bn).
The drop was mainly attributed to last year's reduction of maximum stakes on fixed-odds betting terminals from £100 to £2 in the UK.
However, US net revenue increased 38% to £126.4m, while revenue from the rest of the world rose 71% to £257.4m.
Speaking at the time, Ulrik Bengtsson, CEO of William Hill, told Gambling Insider that, in the long term, it was "not unreasonable" for the operator to expect a 50-50 split between UK and international revenue, especially with the "pace of US growth."
