TESLA chief executive Elon Musk's initial 9 per cent stake purchase in Twitter is being probed by the Federal Trade Commission (FTC), The Information reported on Thursday (Apr 28).

The FTC is looking into whether Musk complied with an antitrust reporting requirement when he bought his stake in the social media company in early April, the report said, citing people with knowledge of the situation.

Companies that fail to abide by rules about reporting significant stock purchases or other acquisitions can be fined up to US$43,792 per day.

After the initial stock purchase, Musk, the world's richest man, offered to buy the company for US$54.20 per share in cash, which Twitter agreed to earlier this week. There is little expectation that Musk's potential purchase of Twitter will be rejected by antitrust enforcers.

The focus of the FTC inquiry is whether Musk bought the stake to influence Twitter's management or if he looked to be a passive shareholder, according to the report.

In his Apr 4 filing with the US Securities and Exchange Commission, Musk characterised his stake as passive.

Twitter said it did not have a comment on the report, while the FTC declined to comment. REUTERS