The reserve may be minute, because if one bank is running short of money, others must be running long by roughly the same amount and the first bank can borrow it back on the interbank market.
"If it fails to achieve this, the consequences could be severe in terms of liquidity hoarding and further breakdown of bank funding markets," Credit Suisse said.
The Bank of Canada today raised its target rate for overnight loans between commercial banks to 1 percent from 0.75 percent, its third increase this year.
That means some banks are effectively paying to hold cash with the ECB rather than risk lending it out, and analysts say it reflects the limited access that some banks have to the interbank market.
To unfreeze the credit markets, the G7 governments could have agreed to underwrite lending between banks across national borders, by using central banks to act as joint counterparties.
Though faulted by many, the bill was also seen by some as the kind of measure that could resuscitate the world's bank-to-bank lending market, which is crucial to keeping the global economy alive.
In Europe, this was reflected in record increases in overnight interest rates, especially for US dollar funding, and a marked decline in traded volumes, in both interbank and swap markets.
In normal times, the federal funds rate would more fully capture firms' costs of overnight borrowing, making it a good foundation from which to calibrate other interest rates.
A rate cut now might not even have been felt: the collapse of Lehman has triggered a mad scramble for cash by banks, driving the interbank-lending rate as high as 6% in recent days.
The average credit-card agreement by the mid-2000s was 30 pages long, and it was loaded with 'double-cycle billing' and 'LIBOR-linked' — terms no one understood.