Tesla founder Elon Musk has been invited to join the board of social media company Twitter, just a day after he paid almost $3 billion to acquire a 9.2% stake in the platform.

However, the board imposed conditions on the billionaire amid speculation that he might launch a bid for the company. He has a personal fortune 10 times more than Twitter’s $30 billion valuation.

Musk, either alone or as a member of a group, will not be allowed to own more than 14.9% of Twitter’s outstanding stock for as long as he’s a board member and for 90 days thereafter.

Twitter CEO Parag Agrawal said in a tweet that the company had been talking to Musk in recent weeks and “it became clear to us that he would bring great value to our Board.”

“He’s both a passionate believer and intense critic of the service which is exactly what we need on @Twitter, and in the boardroom, to make us stronger in the long-term,” said Agrawal who assumed control after the departure of founder Jack Dorsey.

Shares in Twitter rose a further 2% a day after surging by more than a quarter after Musk bought 73.5 million shares in the company.

Handing him a seat on the board may also be a strategic move to dissuade him from setting up a rival social media platform. Musk has openly questioned Twitter’s dedication to free speech and the First Amendment. With 80 million followers on Twitter he is well-equipped to set up a new social network.

In a sign that he would push for changes at Twitter he tweeted on Tuesday that he wants to make “significant improvements to Twitter in coming months”.

On Monday he launched a poll asking whether users want an edit button in order to change their tweets. Such facilities already exist on Facebook and LinkedIn.