There's a quadrillion ways the banks manipulate the value of financial transactions and commodities. Here's a good article on the LIBOR scandal
Libor Woes Threaten to Turn Companies Off Syndicated Loans
Libor is calculated from a daily survey carried out for the British Bankers Association in London, in which the worlds biggest lenders are asked the rate theyre charged to borrow over a variety of short-term maturities in currencies including dollars, euros and yen. Banks are accused of massaging down submissions for the benchmark for $360 trillion of global securities during the financial crisis and artificially increasing them before it.
It's even easier for an idiot lawyer to pull a number out of his ass. As in this case.