Constellation stock is falling again this morning, brushing $60, its lowest level since late 2006. The mojo Constellation got from the BGE rate caps coming off is behind it now. The rate caps disappeared in mid 2006, which reaped huge windfalls for BGE parent Constellation. Why? During deregulation the company took over BGE's former power plants, most of which are driven by coal and nuclear energy. With the deregulated price of electricity being largely set by natural-gas generators, and with natural gas soaring in price, BGE could book huge margin spreads between its cheap fuel costs and the soaring wholesale market price.

That's still largely going on, although the price of coal has zoomed this year, cutting into the cushion. But Wall Street is focusing on other things, such as the profits Constellation makes from playing the energy markets for its own account. Today's column:

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.

The punishment of Constellation is an encouraging sign that Wall Street is again skeptical of companies that depend on opaque accounting and complex financial bets for much of their profit. A little such skepticism for folks betting on subprime mortgages could have saved a lot of heartache.

Read the whole thing here.