Changed by Wall Street, for Wall Street

AND so Liborgate drags on and on and on.

Last week, two senior Washington officials — Timothy F. Geithner, the Treasury secretary, and Gary Gensler, the head of the Commodity Futures Trading Commission — testified before Congress about the scandal surrounding Libor, the benchmark for global interest rates.

No great revelations were forthcoming.

As we await the full story, it’s worth remembering how Libor, the London interbank offered rate, became the world standard to begin with.

You probably won’t be shocked to learn that in mortgages, at least, Wall Street played a role in pushing Libor over another rate benchmark — one that some bankers say was better for borrowers.

Before this scandal made headlines, few people outside of finance knew what Libor was. But according to the Center for Responsible Lending, half of the nation’s adjustable-rate home mortgages are based on it. Since 2002, more than 12 million A.R.M.’s, worth $3.5 trillion, have been indexed to Libor, according to the center.

That’s a lot of money resting on an interest rate that turns out to have been rigged.

Rest here…