(Bloomberg) -- British billionaire Joe Lewis has exited his stake in a biotechnology firm at the center of the US insider-trading case in which he pleaded guilty this week, cementing an eight-fold gain.

Boxer Capital, the firm for Lewis’s biotech investments, offloaded 6.9 million shares in Mirati Therapeutics Inc. on Tuesday when Bristol-Myers Squibb Co.’s acquisition of the cancer drugmaker closed, according to a regulatory filing. The stock was worth about $400 million based on the acquisition price of $58 per share.

That price is about 730% higher than when Mirati started trading in the US in July 2013, the month after Boxer Capital surfaced as a shareholder in the San Diego, California-based firm. Bristol-Myers’ all-cash deal valued Mirati at $4.8 billion and bought out all remaining shareholders of the drugmaker.

Lewis and a trust for his family owned about 90% of Boxer Capital’s Mirati shares, with the balance controlled by executives at the firm.

Boxer Capital’s latest sales came the day before Lewis pleaded guilty to passing inside corporate information to his private pilots and girlfriend, putting a black mark on the 86-year-old investor’s otherwise remarkable rise from London’s East End to one of the richest people in the UK.

Read More: Billionaire Joe Lewis Pleads Guilty in Insider Trading Case

Mirati was one of several companies US federal prosecutors cited in the indictment, which accused him of abusing access to corporate boardrooms and concealing his investments. As part of a plea deal disclosed Wednesday that will likely reduce any sentence for Lewis, his company Broad Bay also pleaded guilty to securities fraud and agreed to pay a $50 million fine.

There’s no suggestion of wrongdoing in the latest share sales by Lewis, who has a net worth of about $7.6 billion, according to the Bloomberg Billionaires Index.

Representatives for Boxer Capital and Lewis declined to comment. Mirati didn’t immediately respond to a request for comment.

‘So Embarrassed’

Mirati was one of the most successful recent bets for Boxer Capital, a San Diego-based investment firm that holds stakes in about 75 US-listed biotech companies worth $1.9 billion, filings show.

Boxer previously disclosed gains from its investments of 7,500% over the past two decades, helping to diversify the fortune that Lewis originally made in the hospitality industry and later turbo-charged with a successful bet on the British pound and Mexican peso during the 1990s.

Read More: Joe Lewis’ Habit of Tipping Off Staff, Lover Ends In Court

Aaron Davis, a former UBS Warburg dealmaker, is chief executive officer of Boxer Capital, where Lewis doesn’t control investing decisions. As part of his plea deal, Lewis agreed to divest any ownership of Boxer Capital by the end of his five-year probation period. 

Boxer Capital kept investing in Mirati the month after Lewis’ arrest on insider-trading charges, paying $27.80 per share, or less than half the company’s eventual takeover price. In 2019, according to prosecutors, Lewis allegedly told several people to buy Mirati shares after hearing that the company had received positive results in a clinical trial.

Lewis, who told Judge Jessica Clarke on Wednesday he was “so embarrassed” by his actions, will appear in court again on April 1.

--With assistance from Ava Benny-Morrison.

(Adds acquisition details in third paragraph)

©2024 Bloomberg L.P.