EXPLAINER: What Elon Musk's dance with Twitter really means

PROVIDENCE, R.I. (AP) — Tesla CEO Elon Musk's great Twitter turnabout — in which he disclosed his massive stake in the social media company, got a seat on its board, publicly floated drastic changes and then turned down the board role — all happened in a week.

But its aftermath could linger if the mercurial billionaire who now holds a roughly 9% stake in Twitter continues to push forward his ideas for reshaping the business of social media.

WHY DIDN'T MUSK JOIN THE BOARD?

Musk said he informed Twitter on Saturday that he wouldn't be joining its board of directors, after being invited five days earlier, according to a financial disclosure. He didn't explain why but the Saturday decision coincided with a barrage of now-deleted tweets from Musk proposing major changes to the company, such as dropping ads — its chief source of revenue — and transforming its San Francisco headquarters into a homeless shelter. Musk left a few clues on Twitter about his thinking, such as by “liking” a tweet that summarized the events as Musk going from “largest shareholder for Free Speech” to being “told to play nice and not speak freely.”

WHAT IS TWITTER SAYING?

Twitter CEO Parag Agrawal said Musk's not joining was “for the best” but didn’t give explicit reasons in a statement Monday. Agrawal also left some clues, noting that Musk had been awaiting a background check and suggesting that Twitter wanted him on the board — rather than just as a major shareholder — because as a fiduciary he’d be legally and ethically bound to act “in the best interests of the company and all of our shareholders.”

HOW DID MUSK BUILD HIS STAKE?

Musk has been tweeting for a long time, but he began buying Twitter stock in earnest only a few months ago. He started on Jan. 31, when he bought a little more than...