Stocks have been on fire of late. The large-cap-heavy S&P 500 is up more than 20% in the past 12 months alone -- and 45% in the past 24 months. So as I've done before, today I'm going to profile the stocks where pessimism is heavy -- the 10 most heavily shorted stocks on major U.S. exchanges.

The list below looks at the 10 stocks with the highest short interest. I've limited this screen to stocks trading on major U.S. exchanges, and to rule out penny stocks, I set a limit of $1 a share and required a minimum market cap of $200 million. Finally, I focused on short interest rather than the largest total short positions, because the latter stat predictably skews toward mega-cap stocks and exchange-traded funds with massive trading volume.

Here are the results:

Company

Short Interest As % of 
Shares Outstanding

Motley Fool CAPS 
Rating (out of 5)

Market Cap

Coinstar (Nasdaq: CSTR)

36.8%

**

$1.7 billion

Rubicon Technology (Nasdaq: RBCN)

36.8%

**

$580.7 million

Blue Nile (Nasdaq: NILE)

34.5%

**

$758.4 million

Northern Oil and Gas (AMEX: NOG)

34.4%

**

$1.3 billion

ATP Oil & Gas (Nasdaq: ATPG)

34.3%

****

$870.9 million

Entropic Communications (Nasdaq: ENTR)

34.3%

***

$795.1 million

ZAGG (Nasdaq: ZAGG)

33.9%

*

$249.7 million

Power-One (Nasdaq: PWER)

32.3%

****

$909.9 million

Constant Contact (Nasdaq: CTCT)

29.4%

*

$782.3 million

McClatchy (NYSE: MNI)

29.4%

*

$242.6 million

Data from Capital IQ (a division of Standard & Poor's) as of May 11. CAPS data from Motley Fool CAPS; out of a possible five stars.

So what?
For balance, I included each stock's Motley Fool CAPS rating, a gauge of the Main Street sentiment. Wall Street sentiment is against these 10 stocks, and with the exception of ATP and Power-One, the CAPS community is either bearish or neutral.

Many are betting on these stocks' demise. That's not to say the short-sellers are always right -- just that if you own them, you should carefully weigh all that pessimism against your investing thesis. And that you should keep closer-than-normal tabs on these stocks, which is easy to do by adding them to your Watchlist.

Fool.com managing editor Brian Richards doesn't own shares of any companies mentioned. Blue Nile is a Motley Fool Rule Breakers selection. The Fool owns shares of Power-One and has a disclosure policy.