Bill Ackman is risking his investors' money on a "vendetta" with his $1 billion short position in Herbalife, Robert Chapman of Chapman Capital said Wednesday on CNBC.
"I am confident that as long as Pershing Square's investors allow Bill Ackman to spend millions of dollars of their money on his personal vendetta, that that guy will never walk into a trading room and voluntarily hand someone a 'buy' order in Herbalife," he said. "I truly believe he's a guy who probably has a poster from the movie '300' hanging over his bed."
(Read more: Herbalife's a $300 stock, Robert Chapman says)
On "Fast Money," Chapman said that he didn't expect Ackman to cover his short position.
"He's not trained in the fine art of surrender, and when he's putting his investors' financial lives at risk, I think he's just going to keep going forward," Chapman added.
Ackman, who announced his massive short position on the nutritional supplement company in January, told CNBC on Wednesday that he hasn't "covered a single share."
(Read more: Ackman to CNBC: I haven't covered Herbalife short)
On the other side of Ackman's position were billionaire investors Carl Icahn and George Soros.
(Read more: Soros takes large Herbalife stake, shares spike)
Asked about the investment that Soros had made, Chapman said, "Well, I know nothing personally about the position he's taken, the size of it or the timing, but I would say it would certainly fit a deep-value investor's profile of a stock to own. And birds of a feather do tend to flock together, and Icahn and Soros having this position would make sense."
Chapman said that the stock was one of his biggest holdings.
"Herbalife constitutes one of the largest positions that I hold in all the accounts," he said, adding that some of his portfolios hold more than 50 percent of stock.
"I've re-established my position in the low 40s and have left it on for the last 20-plus points," Chapman said. "I don't see there's any other position to have in this stock. It's currently traded at only 15 multiple of $5 2013 earnings, gets you to $75 per share. So, even at low $60s, it's something you should own."
Trader disclosure: On July 31, 2013, the following stocks and commodities mentioned or intended to be mentioned on CNBC's "Fast Money" were owned by the "Fast Money" traders: Michael Santoli is long BAC; Michael Santoli is long C; Michael Santoli is long YHOO; Simon Baker is long AAPL ; Simon Baker is long C; Simon Baker is long GS; Simon Baker is long JPM; Simon Baker is long GOOG; Simon Baker is long EBAY; Stephanie Link is long AAPL; Stephanie Link is long JPM; Stephanie Link is long WFC; Stephanie Link is long CSCO; Stephanie Link is long FB; Stephanie Link is long EBAY; Stephanie Link is long TKR; Stephanie Link is long JOY; Stephanie Link is long AIG; Jon Najarian is long AAPL; Jon Najarian is long GS; Jon Najarian is long JPM; Jon Najarian is long XLF; Jon Najarian is long HLF; Jon Najarian is long HUN; Jon Najarian is long MAR; Jon Najarian is long TMO; Jon Najarian is long WLL; Jon Najarian is long SYMC.