The company, which employs 1,300 people in Leeds, confirmed it has received two separate takeover proposals from private equity firm Apollo and casino giant Caesars Entertainment.
The betting business said it received a written proposal from Apollo on August 27, before receiving further proposals from each party.
It told investors that discussions “are ongoing” with both bidders.
In a statement to the London Stock Exchange, it stressed that there “can be no certainty” that any formal offer will be made for the company.
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“The board notes the recent press speculation regarding a possible offer for William Hill,” it said in the statement.
“It confirms that it has received separate cash proposals from Apollo Management International and Caesars Entertainment.”
Caesars already owns a 20% stake in William Hill’s US operations, which also have exclusive rights to operate sports betting under the Caesars brand.
Private equity giant Apollo has also been in the frame to purchase supermarket chain Asda in recent week, with it placing a bid with owner Walmart as part of the ongoing auction for the grocer.