Many investors, especially during earnings season, seem to focus on the income statement. How much revenue was there? How much net income was there? Yet that focus can be dangerous, because the balance sheet actually tells us a lot about how the company is doing, and what it's likely to be doing in the not-too-distant future. Today, I'll focus on two balance sheet line items, accounts receivable (A/R) and inventories, and how they relate to sales.

In Thornton O'Glove's book Quality of Earnings, he calls the analysis of A/R and inventory growth relative to sales the "best method" to get ahead of Wall Street analysts:

One of these simple ploys -- the best method I have ever discovered to predict future downwards earnings revisions by Wall Street security analysts -- is a careful analysis of accounts receivables and inventories. Learn how to interpret these ... a larger than average accounts receivable situation, and/or a bloated inventory. When I see these, bells go off in my head.

If A/R goes up significantly faster than sales, then the company could be stuffing the channel, pulling sales in from the future. It can only do so for so long before customers get fed up and stop buying for a while. Then the company ends up missing revenue and earnings, and the stock price gets whacked.

Similarly, if inventory is rising significantly faster than sales, that could mean demand is slowing down, and a big inventory writedown might be coming. Alternately, sales will be hurt when the company uses large markdowns just to clear out inventory.

Note that I'm not talking about normal business-cycle stuff. Many retailers build up inventory prior to the holiday season in order to meet expected demand. That's normal. Instead, I'm looking for a big disconnect between the growth of sales and the growth of A/R or inventory. That's a potential sign of a risky investment, and it makes me dig a bit deeper to see what's going on.

Let's apply this to Weatherford International (NYSE: WFT), the oil drilling equipment and services company. Here's what the company has reported for the last four-quarter period, and for the last two year-over-year periods. I've also included a couple of others for comparison's sake.

Metric

Weatherford International

Baker Hughes (NYSE: BHI)

Lufkin Industries (Nasdaq: LUFK)

Revenue growth, TTM

(0.8%)

(5.6%)

(25.3%)

A/R growth, TTM

12.8%

51.5%

10.2%

Inventory growth, TTM

4.9%

22%

(7.8%)

       

Revenue growth, year ago

9.7%

1%

16.5%

A/R growth, year ago

3.7%

(14.7%)

(13%)

Inventory growth, year ago

18.4%

6.2%

10.4%

       

Revenue growth, 2 years ago

19.7%

13.4%

1.7%

A/R growth, 2 years ago

21.3%

25.6%

20.4%

Inventory growth, 2 years ago

26%

12.2%

14.5%

Source: Capital IQ, a division of Standard & Poor's; TTM = trailing 12 months.

All three companies have seen growth in A/R over the past year while revenue trended down. Not the best of things to see. Over the past couple of years, Weatherford did alright, except for seeing inventory grow a bit faster last year. Baker Hughes did pretty well, and Lufkin did fine last year, recovering from a worrisome situation two years ago. With the industry dependent on the price of oil and seeing the huge price swings that commodity has had over the past few years, the data above is perhaps not too surprising. Now that oil prices have mostly stabilized (or at least are not going up and down like a yo-yo), investors should expect these companies to get these line items stabilized, as well.

Pay attention to the balance sheet, plug a few numbers into a simple spreadsheet, and, according to O'Glove, you can get ahead of Wall Street. This easy analysis, along with a bit of thought, gives you the potential to save yourself the heartache of seeing your investment get sharply cut when a company reports a "surprisingly" disappointing quarter.

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Fool analyst Jim Mueller doesn't have a position in any company mentioned. He works with the Fool's Stock Advisor newsletter service. Try any of our Foolish newsletter services free for 30 days. The Motley Fool is investors writing for investors.