Another New York billionaire has gone on a dollar-store shopping spree.

Hedge-fund tycoon Bill Ackman vaulted past Wall Street bigwig Nelson Peltz to become the largest shareholder in Family Dollar, a steadily-growing discount chain that has become a Wall Street darling and the subject of intense buyout speculation.

Peltz goosed Family Dollar’s stock in February when he offered to acquire the retailer for more than $7 billion, although he has since battled widespread skepticism that he has the backing or even the genuine desire to get a deal done.

Ackman, who yesterday enlarged his stake to 10.9 million shares, or 8.9 percent — ahead of Peltz’s 6.5 percent stake and up from his first-quarter position of 4.7 percent — meanwhile has recently pooh-poohed Peltz’s offer as too cheap.

“We just don’t like the price,” Ackman said at a conference last month, noting that the offer by Peltz’s Trian Fund Management amounted to $55 to $60 a share. Ackman argued that Family Dollar’s shares were worth more than $70 each and might attract interest from big buyout funds including Blackstone Group.

Family Dollar shares — which were trading below $44 before Peltz disclosed his stake in February — yesterday rose $1.09, or 2.1 percent, to close at $52.57.