A tweet from Tesla boss Elon Musk’s account suggests he is “considering” taking the electric car firm private.
The BBC has been unable to verify the post was written by Mr Musk himself, but it has pushed the shares 6% higher.
The tweet suggested Mr Musk was looking at a plan to buy outstanding shares in the firm for $420 each, around a fifth higher than the share’s current price.
“Funding secured”, the tweet added, offering no further details on timing or source of funding.
Tesla did not respond to a request for comment immediately.
Mr Musk has previously discussed the drawbacks of being a public company, saying shareholder demands often produce short-term thinking.
But it was not clear how seriously to take the post, given Mr Musk’s history on the social media service.
On April Fool’s Day, Mr Musk joked on Twitter about Tesla going bankrupt.