The credit market remains exceptionally tight these days. In spite of (or perhaps because of) Uncle Sam's help, almost no company that actually needs a loan is able to get one from a private lender at decent rates.

In fact, those that can get money at all are forced to pay outrageous interest for the privilege. General Electric, for instance, is paying Berkshire Hathaway 10% on its preferred shares, and GE had to sweeten the pot with warrants to get its rate that low.

And GE is a profitable industrial titan -- once the world's largest company -- that even after its recent downgrade still sports an impressive AA+ debt rating. When a company like that needs to dilute its shares to get money loaned to it at double-digit rates, you know the credit market is tight.

Although it's difficult and expensive, GE can borrow the cash it needs to operate. But not everyone is so lucky.

Who's at the biggest risk?
In a credit environment this tight, companies that can't either roll over their debt, or pay their debt and operate with what they have, are in danger of going under.

But with the possible exception of law firms that handle bankruptcies, nearly every company is feeling the pain of this economic downturn. So how can you tell if a company is struggling just like everyone else -- or about to fail?

These three signs should make you sit up and take notice:

  • A substantial amount of debt -- given this credit market, a company with significant debt that it can't pay off is a huge risk for shareholders.
  • A negative tangible book value -- which means that its total worth is tied up in its brands, its goodwill, and its ability to generate cash, leaving nothing to borrow against.
  • Negative earnings -- which means that it hasn't recently been able to run its business profitably. If that condition doesn't change, those debt holders will soon tire of financing the company's operations.

When you put all three of those high-risk signs together, you get companies like these:

Company

Tangible Book Value

TTM Net Income

Total Debt

Boston Scientific (NYSE:BSX)

($6,263)

($2,371)

$6,247

Genworth (NYSE:GNW)

($981)

($572)

$9,585

Sara Lee (NYSE:SLE)

($617)

($248)

$2,812

Cablevision (NYSE:CVC)

($8,753)

($228)

$11,990

Delta Air Lines (NYSE:DAL)

($14,128)

($3,326)

$16,596

Expedia (NASDAQ:EXPE)

($2,166)

($2,518)

$1,545

Advanced Micro Devices (NYSE:AMD)

($636)

($3,142)

$5,697

All numbers in millions. Data from Capital IQ, a division of Standard & Poor's.

Of course, not every company that shares these traits is on the verge of failure, and I'm not suggesting that the above companies are literally about to fail. Just looking at two examples, Sara Lee and Boston Scientific are showing the aftereffects of non-cash goodwill writedowns. While a sign of overoptimistic expansion plans gone astray, it's not exactly a corporate death sentence.

On the other hand, those three signs in combination often tell of darker days to come. Indeed, Delta has already suffered through a bankruptcy, and recently a competitor of Cablevision (Charter Communications) with precarious financials filed as well.

If a company is in debt, doesn't have enough assets to borrow against, and it isn't generating cash, then it's really only a matter of time before its debt holders get tired of financing its business. That's especially true now.

Buy smarter
In general, companies that hemorrhage cash, have weak balance sheets, and are drowning in debt make lousy investments. On the flip side, those that gush cash, are smart with their use of debt, and have solid balance sheets backing up their businesses can be tremendous companies to own.

That's especially true during times like these when virtually every company has been knocked down off its peak, and even the strongest ones are available at bargain-basement prices.

At Motley Fool Inside Value, we're actively scouring the market to find the solid companies whose shares have been left to rot alongside the truly damaged ones. When we find those diamonds in the rough, we share them with our members, who then have the opportunity to buy some of the world's greatest companies at bargain prices.

If you're ready to avoid the companies teetering on the edge of failure, and instead focus on those with the fundamental strength to thrive in the long run, then join us at Inside Value. Simply click here to learn more or start your 30-day free trial.

This article was originally published March 8, 2009. It has been updated.

At the time of publication, Fool contributor and Inside Value team member Chuck Saletta owned shares of General Electric. The Motley Fool owns shares of Berkshire Hathaway, which is both a Motley Fool Stock Advisor selection and an Inside Value pick. The Fool has a disclosure policy.