San Francisco, Apr 6 (IANS): Tesla CEO Elon Musk may have just picked another battle with the Securities and Exchange Commission (SEC), setting up a potential showdown over how he disclosed his investment in Twitter.

According to Fox Business, the Tesla CEO on Monday disclosed that he had acquired a 9.2 per cent stake in Twitter -- making him its largest shareholder -- in an SEC form that investors are required to file when they own more than 5 per cent of a company.

The filing, dated March 14, revealed that Musk bought about 73.5 million shares for roughly $2.9 billion.

But security law experts say the filing came several days later than it should have because the SEC requires anyone who acquires more than 5 per cent of a company's common share to disclose their holdings with 10 calendar days.

Musk appears to have waited 21 days after March 14 to file the form, the report said.

A spokesperson for Musk did not immediately respond to a request for comment.

On top of that, the document that Musk registered with the SEC -- form 13G -- indicates that he planned to be a passive investor and that he did not intend to take on a larger role with the company.

Those forms require the shareholder to include a certification saying they did not acquire the shares to influence or control the company. Musk did not include that statement on his form; he wrote "not applicable".