21 stocks traders are shorting like crazy

Where you're short, you're betting the value of a stock goes down. But you can quickly lose money when the price goes up.

But sometimes, it pays. Just ask anyone who was short Valeant Pharmaceuticals before the stock dropped 31% over the last two weeks during the controversy over its relationship with specialty pharma Philidor.

We compiled a list of the most shorted stocks in the market. We screened for stocks with market caps of at least $2 billion, and ranked them by short interest, which is the number of shares sold short divided by the total number of outstanding shares (as of November 2).

We included some recent news on the company. And as you'll notice, a lot of the recent news may be somewhere between immaterial to positive. In other words, not all heavily-shorted stocks have big flashing warnings signs screaming "Sell!"

Below are the 21 most heavily-shorted stocks in the market.