Tempted by junk bond yields? Beware of inflation

— -- If you've ever been trapped in traffic and 40 minutes late for a meeting, you know that the wrong question to ask is, "How can things get any worse?" That's usually when the raccoon in the back seat wakes up.

In investing, matters can always get worse, so if you're considering a move into junk-bond funds, you might take a moment to ponder what else could go wrong — such as a burst of inflation.

Junk bonds are long-term, interest-bearing IOUs issued by companies with dubious credit ratings. In some cases, the bonds have been issued by once-strong companies that have fallen from the top tier of the credit ratings — fallen angels, as they're called in the bond market. Other junk bonds were issued by companies that were shaky from the outset.

Whether it was born to junkiness, or had junkiness thrust upon it, a junk bond invariably offers higher yields than bonds issued by companies with higher credit rankings. The reason: The only way a junk bond can attract investors is to offer high yields.

And in general, junk bonds' high yields have made up for a multitude of sins. On average, 4.9% of all junk bonds default each year. But the Lipper high-yield fund index, which measures the returns of the largest junk funds, has gained an average 7.8% per year in the past five years.

In contrast, the average money market fund has gained 2.1% a year over the period. The Lipper government securities fund index has gained 3.6% a year.

But the credit crisis has not been kind to junk-bond funds. Investors have worried that a slowing economy would force more companies to default. When investors worry about defaults, they demand higher yields — which they get by chopping junk-bond prices.

Let's say Raccoon Industries, a start-up company that makes flimsy trash-can liners, issues bonds that yield 6%. The deal: You buy a $1,000 bond, and Raccoon Industries pays you 6%, or $60, every year. When the bond matures, you get your $1,000 back.

Now, say that Raccoon Industries posts a big loss, and the ratings agencies cut the company's credit rating. You decide to sell your bond before it matures.