It isn't enough to compare the spread to its average, Mr. Fridson says, because the average doesn't reflect the current level of default risk, the strength of the economy, the yield on government bonds or the availability of credit.

WSJ: Is It Time to Trash Junk Bonds?

So what level of bleeding is an acceptable risk if patients, on average, live longer?

FORBES: Assessing Avastin's Risk

When you look at the weekly graph for the Philadelphia Semiconductor Index (SOX) you see that semiconductors are on the cusp of its 200-week simple moving average at 341.34 and that a trend below that key technical level indicates risk to its annual value level at 270.98.

FORBES: Connect