By Svea Herbst-Bayliss

BOSTON (Reuters) - Billionaire investor William Ackman revved up his campaign against Herbalife on Monday as investors await the outcome of a U.S. Federal Trade Commission (FTC) probe into the business practices of the nutritional supplements maker.

Ackman's hedge fund, Pershing Square Capital Management, released a video on Monday that it said illustrated what Ackman has called Herbalife's predatory recruiting practices. Ackman said it is the first in a series of videos that he will release this week on his website www.factsaboutherbalife.com.

Herbalife declined to comment. On the company's own website - www.therealbillackman.com - it says the fund manager's "legacy is riddled with losses."

Ackman has waged a four-year campaign against Herbalife, making a $1 billion short bet against it in 2012 and accusing it of running a pyramid scheme which pays members more for recruiting new members than for selling the company's supplements and weight-loss products.

The company has repeatedly denied the allegations, and Ackman has so far lost money on his position.

The FTC opened an investigation into Herbalife in 2014, and in May the company said it was in advanced talks with the consumer protection agency and might settle the probe for $200 million.

On Monday Herbalife's stock rose as much as 3 percent, on a day when equities rallied around the globe. The shares closed up 1.4 percent at $58.82. They have risen 13.28 percent so far this year and are up 122 percent since Ackman first started waging his public campaign against the company.

Once famed for his outsized returns, Ackman has had a rough time lately, clocking a 16.6 percent loss in his Pershing Square International Fund last year and losing 14.5 percent in the same fund through June 7 this year, stung by his bet against Herbalife and a bet on drug company Valeant <VRX.TO>.

Over the last 11 years, Ackman's average annual returns have been 12 percent.

(Reporting by Svea Herbst-Bayliss; Editing by Leslie Adler)