Twitter CEO Parag Agrawal said late Sunday that Elon Musk won’t join the company’s board following ‘many discussions’ with the billionaire Tesla boss.

Updated at 6:39 am EST

Twitter  (TWTR) – Get Twitter, Inc. Report shares slumped lower Monday after the social media group scrapped an agreement to bring Tesla  (TSLA) – Get Tesla Inc Report CEO and billionaire investor Elon Musk onto its board of directors.

Musk, who unveiled a 9.1% stake in the micro-blogging website last week, was due to assume his seat on the board Saturday and had spoken publicly of his desire to bring “significant improvements” to the company. That promise has lead to reports of anxious employees at the group’s San Francisco headquarters, as well as a move by CEO Parag Agrawal to arrange a so-called ‘Ask Me Anything’ session with the newest board member.

Agrawal, however, said late Sunday that Musk has “declined to join our board” following what he called “many discussions”, but declined to elaborate in terms of how the decision was taken.

“I believe this is for the best,”  Agrawal said. “We have and will always value input from our shareholders whether they are on our board or not. Elon is out biggest shareholder and we will remain open to his input”.

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Twitter shares were marked 2.4% lower in pre-market trading to indicate an opening bell price of $45.11 each.

The move could mean Musk, whose stake in Twitter could have only risen to 14.9% were to he take a board seat, can either use some of his vast $300 billion fortune to take Twitter, currently valued at $37 billion, private or simply press from changes as the group’s single-largest shareholder.

Musk’s relationship with Twitter — which he called a “war zone” during his 60 Minutes interview in 2018 — remains complicated, in that he is both a prolific user of the site as well as one of its more vocal critics.

Late last month, Musk said he was giving ‘serious thought” to starting his own social media company, and accused Twitter of “failing to adhere to free speech principles fundamentally undermines democracy” given that the site “serves as the de facto public town square.”