Slowly but surely, America's justice system is waking up to the idea that there is some mileage in going after the banks at the centre of the financial crash of 2008.
Hot on the heels of the Goldman Sachs SEC charges comes an investigation by the New York attorney general Andrew Cuomo into whether eight Wall Street banks misled the big credit ratings agencies so they would give the mortgage securities at the centre of the collapse a clean bill of health.
To which you might say, what took them so long? Such was the breathtaking scale of the crash, and its global ramifications, it seems remarkable that Goldman is the only Wall Street institution to currently be facing charges over its conduct.
Still, the idea that the rating agencies were duped into over-rating mortgage securities lets them off the hook a little too easily.
Some of the tricks played by those packaging up mortgage bonds in the run-up to the crash look less like the work of financial whizzkids pulling the wool over the eyes of innocents and more like ploys that anyone with a bit of commonsense should have seen through.
In particular, the banks sought to get better credit ratings for their bonds in two ways.
They preferred the mortgages of borrowers with little or no credit history at all and who thus had decent individual ratings — known as “Fico scores” in the US — purely because they had no record of transgressions.
And they aimed to package up mortgages so as to produce a decent average Fico score by putting lots of very poor risks together with some good ones.
This is known as barbelling, and statisticians explain the problem with this analogy: “A man with his head in a freezer and feet in an oven is, on average, at room temperature.”
Amazingly, this blatant fixing of the odds seems to have been enough to persuade the ratings agencies to give mortgage securities the all-clear.
When some in the industry did raise concerns they got short shrift.
Possibly it is no coincidence that the ratings agencies were being paid for their work by the very banks whose products they were rating.
It is good to see the authorities trying to bring Wall Street to book for the crash.
But in this case, it may prove difficult to bring charges unless there is a law against exploiting incompetence