Lionsgate Chairman Mark Rachesky is selling 10 million shares of his Lionsgate stock — representing about 20% of his holdings in the studio — with a value of about $330 million.

It’s the first time Rachesky has sold shares in Lionsgate in the decade he’s been invested in the company. And it will bring him a massive profit, since the shares were all acquired prior to 2012 at prices far below the current price.

The sale, announced after the market closed Tuesday, is being made through a secondary offering through his MHR Fund Management LLC, which hold 51.26 million Lionsgate shares and represents a 36% stake.

J.P. Morgan  is the underwriter and is being granted a 30-day option to purchase up to an additional 1.5  million common shares. Lionsgate will not sell any shares in the offering and will not receive any of the proceeds.

The sale will leave Rachesky with a stake of about 28% through MHR, which manages approximately $5 billion in assets. MHR will remain the largest Liongate shareholder.

Rachesky has emerged in recent weeks as one of two final bidders for the Atlanta Hawks of the National Basketball Association, reportedly with

Though final bids are due April 10, the sale of the Hawks franchise is not expected to close for several months. The Hawks franchise was valued earlier this year by Forbes at $825 million.

A report in October said that China’s Alibaba Group, flush with $25 billion in cash after its IPO, was interested in acquiring Rachesky’s Lionsgate stake. That report came three months after Lionsgate and Alibaba had announced they were teaming for a subscription streaming service in China.

Rachesky was named co-chairman in September, 2011, two weeks after Lionsgate settled its bitter four-year dispute with Carl Icahn. Rachesky, a one-time Icahn associate, consistently backed the management of Lionsgate during its prolonged battle with the billionaire investor.

In that 2011 settlement, Rachesky paid $77 million to buy a quarter of Icahn’s 33% stake at $7 a share. Those shares quadrupled in value in the next two years, thanks to Wall Street’s enthusiasm over the “Twilight” and “Hunger Games” franchises, but have since remained in the same range since then.

The shares declined 3.2% in afterhours trading on Tuesday, falling $1.08 to $32.60.

In 2014, Lionsgate agreed to pay $7.5 million and admit wrongdoing to settle Securities and Exchange Commission claims that the studio failed to disclose all information about its 2010 efforts to block a hostile takeover by Icahn. The SEC said Lionsgate management engaged in transactions that allowed Rachesky to boost his stake through newly issued company shares — effectively blocking Icahn’s takeover bid.