LONDON—The $8.7 billion bid battle for Britain’s Morrisons intensified on Monday when a third private equity group entered the fray, sending the supermarket group’s share price racing ahead of the value of an offer it recommended on Saturday. New York-headquartered Apollo Global Management, which last year missed out on buying Morrisons rival Asda, said it was in the preliminary stages of evaluating a possible offer but had not approached its board. Private equity groups have embarked on a spending spree on assets around the world in the last six months, flush with cash after they largely sat out the pandemic. Morrisons, set up 122 years ago as a market stall in northern England, is a target. Morrisons said on Saturday that its board, led by Chairman Andrew Higginson, had recommended a takeover led by SoftBank owned Fortress Investment Group that valued the grocer at £6.3 billion ($8.7 billion). The offer …