(Reuters) -Billionaire investor Bill Ackman's Pershing Square said on Monday it has offered to buy the remaining stake it does not already own in real estate developer Howard Hughes Holdings ( HHH ) for $85 per share.

Shares of Texas-based Howard Hughes, one of Pershing Square's longest-held investments, jumped over 13% in premarket trading.

Howard Hughes's shareholders can elect to receive the entire payment in cash or "roll over" all or a portion of their shares into the post-merger company, Pershing said in a letter.

Howard Hughes has a market capital of $3.6 billion, according to data compiled by LSEG.

Howard Hughes did not immediately respond to a Reuters request for comment.