Elon Musk reverses decision to join Twitter's board

Elon Musk has decided not to join Twitter's board, a move that would have prevented him from increasing his stake in the social media firm beyond 14.9%. 

Twitter CEO Parag Agrawal announced the change of heart in a tweet late Sunday. Agrawal didn't explain Musk's decision, but said he believes it's "for the best."

The news comes five days after Agrawal said Musk was joining Twitter's board, following the billionaire's purchase of a 9.2% stake in the company.

"We were excited to collaborate and clear about the risks," Agrawal said on Sunday. "We also believed that having Elon as a fiduciary of the company where he, like all board members, has to act in the best interests of the company and all our shareholders, was the best path forward. The board offered him a seat."

Musk's appointment was subject to a "background check and formal acceptance" on April 9, but Musk informed Twitter of his decision on the same day.

Musk remains the biggest shareholder of Twitter and Agrawal said the company will remain open to Musk's input.