Should you sell Thermo Fisher Scientific (NYSE: TMO) today?

The decision to sell a stock you've researched and followed for months or years is never easy. If you fall in love with your stock holdings, you risk becoming vulnerable to confirmation bias -- listening only to information that supports your theories, and rejecting any contradictions.

In 2004, longtime Fool Bill Mann called confirmation bias one of the most dangerous components of investing. This warning has helped my own personal investing throughout the Great Recession. Now, I want to help you identify potential sell signs on popular stocks within our 4-million-strong Fool.com community.

Today I'm laser-focused on Thermo Fisher Scientific, ready to evaluate its price, valuation, margins, and liquidity. Let's get started!

Don't sell on price
Over the past 12 months, Thermo Fisher Scientific has risen 16.1% versus an S&P 500 return of 13.7%. Investors in Thermo Fisher Scientific have every reason to be proud of their returns, but is it time to take some off the top? Not necessarily. Short-term outperformance alone is not a sell sign. The market may be just beginning to realize the true, intrinsic value of Thermo Fisher Scientific. For historical context, let's compare Thermo Fisher Scientific's recent price to its 52-week and five-year highs. I've also included a few other businesses in the same or related industries:

Company

Recent Price

52-Week High

5-Year High

Thermo Fisher Scientific $56.54 $57.40 $62.80
Agilent Technologies (NYSE: A) $42.97 $44.45 $44.45
Qiagen (Nasdaq: QGEN) $19.44 $24.00 $24.00
Waters (NYSE: WAT) $76.39 $81.00 $81.80

Source: Capital IQ, a division of Standard & Poor's.

Thermo Fisher Scientific is basically at its 52-week high. This means we need to dig into the valuation to ensure that these new highs are justified.

Potential sell signs
First up, we'll get a rough idea of Thermo Fisher Scientific's valuation. I'm comparing Thermo Fisher Scientific's recent P/E ratio of 23.3 to where it's been over the past five years.

Tmoperatios

Source: Capital IQ, a division of Standard & Poor's.

Thermo Fisher Scientific's P/E is lower than its five-year average, which could indicate the stock is undervalued. A low P/E isn't always a good sign, since the market may be lowering its valuation of the company because of less attractive growth prospects. It does indicate that, on a purely historical basis, Thermo Fisher Scientific looks cheap.

Now, let's look at the gross margins trend, which represents the amount of profit a company makes for each $1 in sales, after deducting all costs directly related to that sale. A deteriorating gross margin over time can indicate that competition has forced the company to lower prices, that it can't control costs, or that its whole industry's facing tough times. Here is Thermo Fisher Scientific's gross margin over the past five years:

Tmogrossmargins

Source: Capital IQ, a division of Standard & Poor's.

Thermo Fisher Scientific is having no trouble maintaining its gross margin, which tends to dictate a company's overall profitability. This is solid news; however, Thermo Fisher Scientific investors need to keep an eye on this over the coming quarters. If margins begin to dip, you'll want to know why.

Next, let's explore what other investors think about Thermo Fisher Scientific. We love the contrarian view here at Fool.com, but we don't mind cheating off of our neighbors every once in a while. For this, we'll examine two metrics: Motley Fool CAPS ratings and short interest. The former tells us how Fool.com's 170,000-strong community of individual analysts rate the stock. The latter shows what proportion of investors are betting that the stock will fall. I'm including other peer companies once again for context.

Company

CAPS Rating

Short Interest (% of Float)

Thermo Fisher Scientific 5 0.7
Agilent Technologies 3 1.7
Qiagen 5 2.4
Waters 5 1.9

Source: Capital IQ, a division of Standard & Poor's.

The Fool community is rather bullish on Thermo Fisher Scientific. We typically like to see our stocks rated at four or five stars. Anything below that is a less-than-bullish indicator. I highly recommend you visit Thermo Fisher Scientific's stock pitch page to see the verbatim reasons behind the ratings.

Here, short interest is at a mere 0.7%. This typically indicates few large institutional investors are betting against the stock.

Now, let's study Thermo Fisher Scientific's debt situation, with a little help from the debt-to-equity ratio. This metric tells us how much debt the company's taken on, relative to its overall capital structure.

Tmototaldebttoequity

Source: Capital IQ, a division of Standard & Poor's.

Thermo Fisher Scientific has been taking on some additional debt over the past five years. When we take into account increasing total equity over the same time period, this has caused debt-to-equity to decrease, as seen in the above chart. Based on the trend alone, that's a good sign. I consider a debt-to-equity ratio below 50% to be healthy, though it varies by industry. Thermo Fisher Scientific is currently below this level, at 14.1%.

The last metric I like to look at is the current ratio, which lets investors judge a company's short-term liquidity. If Thermo Fisher Scientific had to convert its current assets to cash in one year, how many times over could the company cover its current liabilities? As of the last filing, Thermo Fisher Scientific has a current ratio of 2.36. This is a healthy sign. I like to see companies with current ratios equal to or greater than 1.5.

Finally, it's highly beneficial to determine whether Thermo Fisher Scientific belongs in your portfolio -- and to know how many similar businesses already occupy your stable of investments. If you haven't already, be sure to put your tickers into Fool.com's free portfolio tracker, My Watchlist. You can get started right away by clicking here to add Thermo Fisher Scientific.

The final recap

Tmosellingrecap

Thermo Fisher Scientific didn't fail any of the quick tests that would make it a sell. This is great, but does it mean you should hold your Thermo Fisher Scientific shares? Not necessarily. Just keep your eye on these trends over the coming quarters.

Remember to add Thermo Fisher Scientific to My Watchlist to help you keep track of all our coverage of the company on Fool.com.

If you haven't had a chance yet, be sure to read this article detailing how I missed out on over $100,000 in gains through wrong-headed selling.

Jeremy Phillips does not own shares of the companies mentioned. Thermo Fisher Scientific is a Motley Fool Inside Value choice. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.