The full lineup of Standard & Poor's Corp.'s credit ratings gets more befuddling all the time.

Even though S&P this month cut the U.S. government's credit rating to double-A-plus, from an earlier triple-A, the ratings company is far less parsimonious in handing out its highest ratings to other borrowers. As Bloomberg's Zeke Faux and Jody Shenn report today, S&P currently assigns a triple-A rating to more than 14,000 securitized bonds in the U.S.

Those triple-A credits include bonds backed by car-dealer loans and farm-equipment leases: two types of borrowings known for higher default rates in economic slumps. S&P also keeps awarding triple-A ratings to some securities backed by subprime home loans, a type of investment that fared disastrously after housing prices began slumping in 2007-08.

At least investors aren't regarding a top-tier credit rating as an automatic assurance of anything. Market participants currently are demanding about a 4 percent yield on some mortgage bonds due to get triple-A ratings. The U.S. government can borrow at comparable maturities for one-twentieth of the cost, its lower rating notwithstanding.

When market pricing is so profoundly at odds with the ratings hierarchy, it's usually a sign that the credit analysts missed something.