Billionaire Steven A. Cohen's investments gained 7.5 percent in the first three months of 2015, according to a person familiar with the numbers, helping the former hedge fund manager extend his string of market-beating returns.

Cohen's Point72 Asset Management, which invests the Cohen family's $11 billion fortune, handily outperformed the broader stock market this year after the Standard & Poor's 500 index climbed less than 1 percent since January 1. The average hedge fund has gained 2.18 percent this year, research firm Hedge Fund Research reported.

Federal prosecutors forced Cohen to shut down his hedge fund SAC Capital and return money to outside investors after the fund pleaded guilty to insider trading charges.

He changed the name to Point72 Asset Management to underscore a break with the past. But Cohen's returns, which had long generated envy on Wall Street, have continued to be strong, people who used to invest with him and are still following his performance said.

Cable news channel CNBC first reported the numbers.

Other hedge funds are expected to relay first-quarter returns to their investors in the coming days and weeks.