You might be under the impression with that with the stock market indexes hitting fresh year-to-date lows this week, there aren't many companies near 52-week highs. Let me assure you, there are more than 300 within 8% of a new 52-week high. For optimists, these rallies may seem like a dream come true. For skeptics like me, they're opportunities to see whether companies trading near their 52-week highs have actually earned their current valuations.

Keep in mind that some companies deserve their current valuations. With volatility soaring as Greek worries mount, it's not surprising to see Duke Energy (NYSE: DUK) inching toward a new 52-week high. With a very low beta of 0.37 and a dividend north of 5%, it offers stability in a very unstable market.

Still, other companies might deserve a kick in the pants. Here's a look at three companies that could be worth selling.

Standing on the edge
The pharmaceutical sector is both the boon and bane of my existence. In practically no other sector can you find margins regularly north of 70%. Likewise, in no other sector will you find products that have a time limit placed on their exclusivity. I've expounded on the dreaded effects of the patent cliff before, and this week's contestant is Bristol-Myers Squibb (NYSE: BMY).

Bristol-Myers, in partnership with Sanofi (NYSE: SNY), markets the second-best selling drug in the world, Plavix, which is an anti-clotting agent. Unlucky for these two, Plavix is set to lose patent exclusivity in May 2012, which accounted for $9.4 billion in total global sales last year. Avapro, Bristol-Myers' high-blood pressure drug, is also on the chopping block in 2012, accounting for $1.2 billion in sales in 2010. With no quick pipeline replacements in sight and the company trading for a rather pricey 16 times forward earnings, it's hard to justify being a Bristol bull when peers like Pfizer (NYSE: PFE) trade at only 8 times forward profit projections.

To the moon, Alice
Sometimes a large sector merger isn't what the doctor ordered. In the case of the aerospace and defense sector, where rumors are buzzing left and right ever since United Technologies (NYSE: UTX) agreed to purchase Goodrich, investors could be left holding onto hope rather than actual potential.

Since the announced mega-merger, shares of Astronics (Nasdaq: ATRO), which sells aerospace and test system components to airplane manufacturers and the U.S. government, have nearly rallied to a new 52-week high on the hope that it may be the next takeover candidate. Well, folks, based on its current valuation, I simply don't see that happening.

Over the past decade, Astronics has produced only $10 million or more in free cash flow three times and currently trades at an astronomical 33 times operating cash flow. Even at 18 times forward earnings, there are countless cheaper alternatives, especially considering the cutbacks that may be looming in the defense sector next year in response to the U.S. debt-ceiling legislation passed in August.

TreeHouse of horrors
OK, so I completely ripped that title from The Simpsons, but it's very befitting of food manufacturing company TreeHouse Foods (NYSE: THS).

As fellow Fool Anand Chokkavelu recently chronicled, TreeHouse Foods is one of the fastest-growing food stocks, but I think its valuation could be way ahead of its true earning potential. Although 2.1 times book value and 1.1 times sales may not seem all that overpriced, they represent historically high figures for the stock. Moreover, the company's multiple of 11 times cash flow is its highest value since 2009, even though that its return on equity has fallen steadily over the past two years. TreeHouse Foods is still a growth story, but prudent heads need to prevail.

Foolish roundup
It doesn't hurt every once in a while to step back and look at the bigger picture. These three companies have all of the momentum right now, but patent expirations, the rumor mill, and calmer heads could just as easily send them the opposite direction.

What's your take on these three stocks? Are they sells or belles? Share your thoughts in the comments section below and consider adding Bristol-Myers Squibb, Astronics, and TreeHouse Foods to your Watchlist to keep up on the latest news with each company.