The departure of star trader Greg Coffey may cost GLG Partners as much as $4 billion in investor redemptions. Holding on to its star trader will cost Fortress Investment Group $300 million.

The hedge fund and private equity giant has given a $300 million share grant to Adam Levinson, who co-manages that firm’s $8.8 billion flagship global macro fund, The Wall Street Journal reports. The 31 million shares will vest over time, ensuring that he remains with the firm if he wants the full package.

With the grant, Levinson joins five other controlling shareholders of Fortress, who own 77% of the business. The grant increases the number of shares in Fortress—which went public 18 months ago and has seen its stock price fall by two-thirds—by 7%. In exchange for the shares, Levinson’s profit-sharing interest in some Fortress funds will be cut, according to a filing with the Securities and Exchange Commission.

Levinson has been with Fortress since 2002, when he joined from Goldman Sachs.