Twitter stock surged in Tuesday trading because Elon Musk is ready to buy Twitter for $44 billion, after all.

The billionaire has proposed proceeding with his acquisition of Twitter at $54.20 a share.

Twitter stock was up 13% to $47.93 in Tuesday afternoon trading, before being halted because of the news report. Bloomberg, citing people familiar with the matter, first reported that Musk had sent a letter to Twitter proposing to go through with the original deal. Late afternoon Tuesday, Musk disclosed the letter in a filing with the Securities Exchange Commission. Shares then resumed trading and closed up 22% at $52.