This column from Aug. 15, when CEG's stock began tanking after it revealed it had miscalculated collateral contingencies, helps explain what's going on.

A few sentences on page 46 of a financial disclosure that did not change reported profits, sales or net worth caused Constellation Energy Group's prospects to go into brownout this week.

Its shares dropped 16 percent Tuesday. Analysts rushed to downgrade the stock, although one contrarian changed his recommendation from "underperform" to "hold" because the shares had fallen so far.

Standard & Poor's downgraded Constellation bonds to two steps above "junk" status.

A little jumpy, aren't we? Not at all.

Read the whole thing here.