Pressure is building on New York Knicks owner James Dolan to pump up the value of the failing basketball team by selling off stakes to wealthy investors.

On Wednesday, activist investor Clifton S. Robbins said he’s been prodding Dolan’s Madison Square Garden to score minority buyers for the Knicks and Rangers ahead of a planned spinoff that will separate MSG’s sports teams from its other assets, like Radio City Music Hall.

Robbins, whose Blue Harbour Group hedge fund owns a 4 percent stake in MSG, said he thinks the Knicks and Rangers combined should be worth $7.2 billion, far higher than the $5.55 billion price tag they have been given by Forbes. And he suggested they might get closer to that value if Dolan would get off the sideline and find new investors ahead of — or in conjunction with — the 2020 spinoff.

Robbins revealed the push in an interview with Bloomberg News just three days after The Post exclusively reported that buyout firm Silver Lake Partners has approached MSG with just such an offer.