Hedge fund billionaire Carl Icahn tweeted on Friday that he has accepted Donald Trump's offer to be Treasury secretary.

On June 18, in an appearance on MSNBC, Donald Trump said that if he were elected president, "I'd love to bring my friend Carl Icahn" as Treasury secretary.

The next day, Carl Icahn published a letter on his website politely declining Trump's offer.

In that June 19 letter, Icahn said, "I was extremely surprised to learn that Donald was running for President and even more surprised that he stated he would make me Secretary of Treasury. I am flattered but do not get up early enough in the morning to accept this opportunity."

But after last night's debate, it seems he was swayed.

Carl Icahn was not available for comment.