Negotiations were held last summer with the US casino group about a potential £3bn takeover by Caesars for a combination of cash and shares, the Sunday Times reported.
However, by August the FTSE 250 bookie and the Caesars Palace casino and hotel owner had failed to come to an agreement over the takeover price and the talks were nixed.
William Hill’s valuation has since slumped to just under £1.2bn, not helped by a huge write-down of its UK betting shops, as its shares have more than halved from just under 300p at the start of August to finish last week at just over 134p.
Under chief executive Philip Bowcock, Willian Hill fought off takeover bids from rivals Rank and 888 in 2016, before an ambitious attempt to merge with Canada’s Amaya failed.
Caesars, which is valued at almost $5.9bn on Wall Street, has been put under pressure to pursue deals by activist investor Carl Icahn, amid falling sales in Las Vegas last year.
In March, newswires reported that Caesars was in talks with Eldorado Resorts Inc (NASDAQ:ERI) about a possible merger.
William Hill shares spiked as high as 140p on Monday morning but were soon back in the red, down almost 2% to 131.45p.