• Tesla and SpaceX CEO Elon Musk abandoned his plans to join the board of Twitter after buying a 9% stake.
• Twitter CEO Parag Agrawal wrote in a company announcement he shared on Twitter, "There will be distractions ahead but our goals and priorities remain unchanged."
• Musk's appointment would have started April 9, contingent on a background check and formal acceptance.

Tesla and SpaceX CEO Elon Musk has abandoned his plans to join the board of Twitter, his social network of choice.

Twitter CEO Parag Agrawal announced publicly Sunday that Musk remains the largest shareholder of Twitter, and the company will remain open to his input.

Musk informed Twitter on Saturday morning that he would not, in fact, take the board seat.

Twitter's stock briefly tumbled more than 8% to less than $43 a share in premarket trading Monday, but closed up 1.69% on the day.

Musk's appointment would have started Saturday, "contingent on a background check and formal acceptance," according to Agrawal.

"We were excited to collaborate and clear about the risks. 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," he wrote.

The Twitter CEO did not say whether Musk gave specific reasons for changing his mind about taking on the new obligation.

Encouraging company employees to remain focused, Agrawal said, "There will be distractions ahead but our goals and priorities remain unchanged."

On April 5, Elon Musk and Twitter said he would be joining Twitter's board. A day earlier, the Tesla CEO and world's richest person disclosed via financial filings that he's the social media company's biggest shareholder.

Twitter's stock jumped 4% on Tuesday following the board announcement before ending the day up 2%. On Monday, after Musk's stake was initially revealed, the company had its best day since its IPO in 2013, skyrocketing more than 27%. 

A financial filing from Twitter specified that as long as Musk served on its board, he would be limited to owning no more than a 14.9% stake in the company's common stock outstanding, including through derivative securities, swaps, or hedging transactions.

Musk could theoretically increase his 9% stake beyond that limit now.

Throughout the weekend, without revealing that he had turned down the board seat at Twitter, Musk posted a number of ideas to transform the social media company and its products.

One of the suggestions was a coarse joke in the form of a Twitter poll. Musk asked people to vote on whether Twitter should drop the "w" from its name. Doing so would turn Twitter into "titter," an allusion to female anatomy.

More serious suggestions from Musk included to let Twitter Blue subscribers pay with dogecoin, get an "authentication" checkmark and keep Twitter Blue free of advertisements.

"Everyone who signs up for Twitter Blue (ie pays $3/month) should get an authentication checkmark," Musk wrote. "And no ads. The power of corporations to dictate policy is greatly enhanced if Twitter depends on advertising money to survive."

Musk also suggested that Twitter should turn its headquarters office in San Francisco into a homeless shelter, "since no one shows up anyway."

Musk's competitor and fellow centibillionaire, Jeff Bezos, chimed in. Bezos said Twitter could turn a portion of its office into a shelter. "Worked out great and makes it easy for employees who want to volunteer," he said sharing a story about a similar initiative at Amazon.

Correction: This story has been updated to correct the date of when Twitter and Elon Musk said he would be joining the board.