Billionaire investor Bill Ackman's Pershing Square has submitted a proposal to purchase 10 million newly issued shares of Howard Hughes Holdings (HHH) at $90 each.

The purchase would give Pershing Square ownership of 48% of stock. As part of the deal, Ackman would become chairman and CEO of the real estate developer, according to Ackman's post on X.

"We will make available the full resources of Pershing Square to HHH to build a diversified holding company, or one could say, a modern-day Berkshire Hathaway," Ackman wrote on X. "The new HHH will acquire controlling interests in private and public companies that meet Pershing Square's criteria for business quality."

Howard Hughes' shares rose about 6% in afternoon trading after Ackman tweeted he would be making the announcement after Tuesday's market close. But shares fell about 4% in after-hours trading once Ackman posted the details of the plan.

This marks Ackman's second bid for Howard Hughes. In January, Ackman proposed a deal to buy 11.8 million shares at roughly $85 per shares.

In a post prior to the announcement, Ackman likened his firm's move to the approach Warren Buffett has used with Berkshire (BRK-A, BRK-B) in which Buffett turned a textile manufacturer into a holding company that owns stakes in many publicly traded equities including Apple (AAPL) and Bank of America (BAC).

"We will adopt similar, long-term, shareholder-oriented principles to Berkshire, and we intend to hold the stock forever," Ackman wrote in his post previewing the announcement.

According to a Securities and Exchange Commission filing dated Dec. 31, Pershing Square ended 2024 with stakes in Brookfield (BN), Restaurant Brands (QSR), Chipotle (CMG) and Howard Hughes. In recent weeks Ackman also announced he'd purchased more than 30 million shares of Uber in early January.

Ackman will be hosting a question and answer session for investors on X regarding the proposed deal at 9 a.m. ET on Wednesday morning.