In the first of two opportunities to get the 3-year money, the ECB alloted 489 billion euros to euro zone banks last Wednesday, with lenders receiving the funds as markets closed for Christmas on Friday.
The liquidity injection was the ECB's latest and most dramatic effort to bolster banks' finances, in a move it hopes will minimise the chances of them responding to the euro zone's debt turmoil by slamming the brakes on lending.
Three-month Euribor rates, traditionally the main gauge of unsecured interbank euro lending and a mix of interest rate expectations and banks' appetite for lending, fell to 1.396 percent from 1.404 percent on Tuesday after the flood of new cash entered the financial system.
Longer-term rates also fell. Six-month rates eased to 1.648 percent from 1.658 percent, while 12-month rates eased to 1.976 percent from 1.988 percent.
Shorter-term one-week rates - most heavily influenced by excess liquidity, which remained high at 470 billion euros according to Overnight rates fell to 0.422 percent from to 0.509 percent.
The recent intensification of the euro zone debt crisis has left a growing pack of banks virtually locked out of open funding markets and reliant on the ECB.
Last Thursday, the European Systemic Risk Board said the dangers facing Europe's financial system had continued to worsen over the last three months.
In response the ECB has already reinstated some of its most potent crisis-fighting tools.
But banks still appear to distrust each other and prefer to deposit their money at the ECB's overnight facility than lend to each other. Latest figures show banks deposited 412 billion euros at the central bank. Emergency overnight borrowing also remained high at above 6 billion euros.