Hedge fund horror show as Valeant gets crushed

Hedge fund darling Valeant Pharmaceuticals is getting hammered after short-selling firm Citron Research published a report comparing it to Enron.

The Canadian drug company's stock was last down about 25% at around $110. It had fallen as low as $88.50.

The stock has been popular among hedge funds.

It ranked No. 10 on Goldman Sachs' stocks that "matter most" to hedge funds list for the second quarter. According to Goldman, 32 funds had the stock as one of their top 10 stock holdings.

Here's a quick rundown of the top five biggest hedge fund holders, according to regulatory filings compiled by Bloomberg.

These are positions the funds held for the second quarter ended June 30. They could have traded in or out of those positions.

1. Pershing Square (Bill Ackman): 19,472,993 shares, 5.71%
2. ValueAct Holdings (Jeff Ubben): 14,994,261 shares, 4.39% (sold 4.39 million shares in Q2)
3. Paulson & Co. (John Paulson): 9,000,000 shares, 2.64% (added 6.95 million shares in Q2)
4. Lone Pine Capital (Steven Mandel): 5,310,143 shares, 1.56% (sold 259,317 shares in Q2)
5. Viking Global (Andreas Halvorsen): 4,616,738 shares, 1.35% (added 558,395 shares in Q2)

Ackman, who runs $19 billion Pershing Square Capital, is the largest hedge fund shareholder. Valeant is his fund's largest stock holding. He has likely lost more than $1 billion on paper on his big Valeant bet.

Others are likely feeling the pain, too.