Twitter Chief Executive Parag Agrawal said in a note posted to Twitter that the company's board held many discussions with Musk, but he did not state the reason for the Tesla (TSLA.O) CEO's decision.

Axar.az reports that agrawal said the planned appointment was due to become effective on Saturday, which would have prevented the world's wealthiest person from becoming a beneficial owner of more than 14.9% of Twitter's common stock.

"I believe this is for the best," Agrawal said in the note. "There will be distractions ahead, but our goals and priorities remain unchanged."

The announcement was so abrupt that Musk was still listed on Twitter's board of directors on its website as of early Monday.

Twitter shares were down about 4% in premarket trading on Monday. They soared 27% on April 4 after Musk disclosed his stake but have since lost 7.5%.