Valeant's stock is getting stomped again

Shares of Canadian pharmaceutical company Valeant cratered again on Thursday morning.

The share price was last down 15% at about $101.57. So far this week, the stock has fallen more than 42%.

The stock fell on Wednesday after short-selling-firm Citron Research published a report accusing Valeant of being an Enron-like fraud.

Much of Citron's report focuses on Valeant's mysterious relationship with Philidor, a specialty pharmacy that distributes and books prescription drugs for big drug companies.

Valeant is the only customer of Philidor and it also has an option to buy the company. Citron accuses Valeant of using Philidor, and an unknown number of specialty pharmacies like it to generate fake invoices so that it can book revenue for sales that never happened.

The report also draws comparisons to Enron that are "too close to ignore."

"We categorically deny the allegations made in the Citron Report," Valeant said in a statement. "Citron's false and misleading statements about Valeant appear to be an attempt to manipulate the market in an effort to drive down Valeant's stock price."

A number of Wall Street analysts have weighed in on the matter. The reaction has been mixed. Some see the share price collapse as a buying opportunity, while others think it's best to wait it out. Others just don't know.

Valeant has been a popular stock amongst 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.

Activist investor Bill Ackman, the founder of $19 billion Pershing Square Capital Management, is the largest hedge fund shareholder and the third largest shareholder overall. He's lost more than $1 billion on paper on the position so far. During Wednesday's decline, Ackman said that he bought 2 million more shares, bringing his total stake to 21.47 million shares.

Here's a five day chart: