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.

Silver Lake, which already owns close to 10 percent of MSG, has proposed taking a bigger stake in MSG’s sports teams than it will otherwise get when they are spun off in the first quarter, as The Post reported Nov. 3.

It’s not the first time Dolan, who’s notoriously unpopular with fans, has been urged to loosen his grip on the Knicks, as he himself admitted in a 2017 video he made for Deadspin.

“You know, I own a basketball team. For most people that would be a dream. For a trust fund kid, it’s a living hell. Always some a–hole telling me to sell,” said Dolan, who’s the son of Cablevision’s founder.

Dolan will continue to control the Knicks and Rangers under the spinoff, which gives MSG’s current shareholders two-thirds of the new stock, because his one-third stake will come with supercharged voting powers, company filings show.

MSG, which declined to comment, has previously said it’s open to selling some of the one-third stake it plans to retain so it can invest in its other businesses, including the futuristic, orb-like entertainment globes Dolan is building in Las Vegas and London.

Shares of MSG, which Robbins said should be worth $400 a piece, closed up 1.6 percent, to $275.72.