Bill AckmanReuters/ Shannon Stapelton

Hedge fund manager Bill Ackman, who is famously short Herbalife, is probably pretty pleased with the news that the Federal Trade Commission will probe Herbalife. 

Until now, his $1 billion bet that Herbalife will plummet to $0 hasn't played out in his favor.  

The most recent estimate was that Ackman had suffered $500 million in paper losses.  

He's made back some of that money just now.

In December 2012, Ackman said he was shorting about 20 million shares of Herbalife.

However, he ended up repositioning his short in October 2013 by swapping about 40% of the equity short for put options.

Based on that, we would estimate that he has about 12 million shares in his equity short (That would be 60% of the original before it was repositioned.) With the stock down by around $6 today, we'd estimate he's made back around $72,000,000 on what he's lost, according to our calculations.  

Herbalife's stock, which was halted, is was last trading down about 9%. Shares of Herbalife hit a low of $54.68, or 17%, at one point after the FTC news came out. 

Ackman believes that Herbalife, a multi-level marketing company that sells nutritional products, operates as a pyramid scheme. He thinks regulators like the FTC will investigate and shut the company down.