Should you sell Parker Hannifin (NYSE: PH) 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 Parker Hannifin, ready to evaluate its price, valuation, margins, and liquidity. Let's get started!

Don't sell on price
Over the past 12 months, Parker Hannifin has risen 53.2% versus an S&P 500 return of 13.7%. Investors in Parker Hannifin 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 Parker Hannifin, which manufactures things for industrial, aerospace, and climate-control uses. For historical context, let's compare the company'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

Parker Hannifin $89.23 $89.44 $89.40
Cooper Industries (NYSE: CBE) $61.42 $61.50 $61.50
Danaher (NYSE: DHR) $46.89 $47.96 $48.00
Donaldson (NYSE: DCI) $59.68 $60.00 $60.00

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

Parker Hannifin 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 Parker Hannifin's valuation. I'm comparing the company's recent P/E ratio of 19.9 to where it has been over the past five years.

Phperatios

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

Parker Hannifin's P/E is higher than its five-year average, which could indicate the stock is overvalued. A high P/E isn't always a bad sign, since the company's growth prospects may also be increasing alongside the market's valuation. However, it definitely indicates that, on a purely historical basis, Parker Hannifin looks expensive.

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 Parker Hannifin's gross margin over the past five years:

Phgrossmargins

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

Parker Hannifin is having no trouble maintaining its gross margin within a range of 2 percentage points. This is solid news; however, Parker Hannifin investors need to keep an eye on this over the coming quarters. If margins begin to drop, you'll want to know why.

Next, let's explore what other investors think about Parker Hannifin. 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)

Parker Hannifin **** 1.8
Cooper Industries *** 1.2
Danaher **** 0.9
Donaldson *** 2.1

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

The Fool community is rather bullish on Parker Hannifin. 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 Parker Hannifin's stock pitch page to see the verbatim reasons behind the ratings.

Here, short interest is at a mere 1.8%. This typically indicates few large institutional investors are betting against the stock.

Now, let's study Parker Hannifin'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.

Phtotaldebttoequity

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

Parker Hannifin has been taking on some additional debt over the past five years. Even with increasing total equity over the same time period, debt-to-equity has increased, as seen in the above chart. Based on the trend alone, that's a bad sign. I consider a debt-to-equity ratio below 50% to be healthy, though it varies by industry. Parker Hannifin is below this level, at 43.7%.

The last metric I like to look at is the current ratio, which lets investors judge a company's short-term liquidity. If Parker Hannifin 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 latest filing, Parker Hannifin has a current ratio of 1.82. 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 Parker Hannifin 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 Parker Hannifin.

The recap

Phsellingrecap

Parker Hannifin has failed only two of the quick tests that would make it a sell. This is great, but does it mean you should hold your Parker Hannifin shares? Not necessarily. Just keep your eye on these trends over the coming quarters.

Remember to add Parker Hannifin 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 more than $100,000 in gains through wrong-headed selling.

Jeremy Phillips does not own shares of the companies mentioned.

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.