Twitter shareholder Elon Musk is reportedly being investigated by the SEC. Again.

Elon Musk is reportedly being investigated by the Securities and Exchange Commission over failure to disclose his significant purchase of Twitter stocks within the mandated time frame. According to The Wall Street Journal, this delay may have saved him over $143 million.

The Wall Street Journalreports that Tesla's CEO and Twitter's imminent owner is in trouble with the SEC yet again, with the federal government scrutinising Musk's investment in Twitter earlier this year. Under the Securities Exchange Actof 1934, investors who acquire over 5 percent of a publicly traded company are required to file a report notifying the SEC within 10 days of the acquisition. Musk bought enough Twitter shares to pass this 5 percent threshold on March 14, putting the deadline for disclosure at March 24.

However, rather than notifying the SEC of his shiny new Twitter stocks, Musk waited until the deadline passed before buying even more shares, putting his stake at 9.2 percent. The billionaire only filed his report with the SEC on April 4, 11 days after he was required to do so for the first purchase.

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Twitter's stock price predictably shot up after Musk's disclosure, closing 27 percent higher on the first day as the market took notice of his interest in the microblogging platform. Musk's delay in disclosing thus gave him a window to purchase additional shares at a lower price than it would have otherwise sold for — an opportunity he took full advantage of.

Musk's tardiness and subsequent gain also came at a cost to other traders. In April, the billionaire became the subject of a proposed class action brought by former Twitter shareholders, who had sold their shares between the date Musk was obligated to report his stake and the date on which he actually did.

It isn't clear what consequences Musk might face if the SEC does decide to take action against him. But whatever it is, chances are he and his $224 billion net worth will just shrug it off. After all, Musk hasn't shown much respect for the SEC nor contrition for his actions in the past.