In Rolling Stone, the amazing Matt Taibbi documents a breaking price-rigging scandal involving the world's biggest banks. The $500 trillion conspiracy to game the interest-rate swaps victimizes every city, town, state and nation that uses bonds to raise money, diverting an unimaginable sum from tax coffers to the pockets of mega-rich bankers. If you've been staring around at the empty storefronts, closed libraries and schools, homeless and breadlines since 2008 and wondering "Where did all the money go?" then wonder no longer.

Though interest-rate swaps are not widely understood outside the finance world, the root concept actually isn't that hard. If you can imagine taking out a variable-rate mortgage and then paying a bank to make your loan payments fixed, you've got the basic idea of an interest-rate swap.

In practice, it might be a country like Greece or a regional government like Jefferson County, Alabama, that borrows money at a variable rate of interest, then later goes to a bank to "swap" that loan to a more predictable fixed rate. In its simplest form, the customer in a swap deal is usually paying a premium for the safety and security of fixed interest rates, while the firm selling the swap is usually betting that it knows more about future movements in interest rates than its customers.

Prices for interest-rate swaps are often based on ISDAfix, which, like Libor, is yet another of these privately calculated benchmarks. ISDAfix's U.S. dollar rates are published every day, at 11:30 a.m. and 3:30 p.m., after a gang of the same usual-suspect megabanks (Bank of America, RBS, Deutsche, JPMorgan Chase, Barclays, etc.) submits information about bids and offers for swaps.

And here's what we know so far: The CFTC has sent subpoenas to ICAP and to as many as 15 of those member banks, and plans to interview about a dozen ICAP employees from the company's office in Jersey City, New Jersey. Moreover, the International Swaps and Derivatives Association, or ISDA, which works together with ICAP (for U.S. dollar transactions) and Thomson Reuters to compute the ISDAfix benchmark, has hired the consulting firm Oliver Wyman to review the process by which ISDAfix is calculated. Oliver Wyman is the same company that the British Bankers' Association hired to review the Libor submission process after that scandal broke last year. The upshot of all of this is that it looks very much like ISDAfix could be Libor all over again.

"It's obviously reminiscent of the Libor manipulation issue," Darrell Duffie, a finance professor at Stanford University, told reporters. "People may have been naive that simply reporting these rates was enough to avoid manipulation."

And just like in Libor, the potential losers in an interest-rate-swap manipulation scandal would be the same sad-sack collection of cities, towns, companies and other nonbank entities that have no way of knowing if they're paying the real price for swaps or a price being manipulated by bank insiders for profit. Moreover, ISDAfix is not only used to calculate prices for interest-rate swaps, it's also used to set values for about $550 billion worth of bonds tied to commercial real estate, and also affects the payouts on some state-pension annuities.

So although it's not quite as widespread as Libor, ISDAfix is sufficiently power-jammed into the world financial infrastructure that any manipulation of the rate would be catastrophic – and a huge class of victims that could include everyone from state pensioners to big cities to wealthy investors in structured notes would have no idea they were being robbed.