The Securities and Exchange Commission is scrutinising internal communications by OpenAI chief executive Sam Altman as part of an investigation into whether the company’s investors were misled.

The regulator, whose probe hasn’t previously been reported, has been seeking internal records from current and former OpenAI officials and directors, and sent a subpoena to OpenAI in December, according to people familiar with the matter. That followed the OpenAI board’s decision in November to fire Altman as CEO and oust him from the board. At the time, directors said Altman hadn’t been “consistently candid in his communications,” but didn’t elaborate.