The EU's New Interest Rate Benchmarks.

WHAT, not WHO, is Ester.
The benchmark for interest rates, in the Euro is, typically, the Euro Overnight Indexed Average, abbreviated as EONIA, and, the Euro interbank offered rate, abbreviated as EURIBOR.
While these are based on actual borrowing, and lending in the Euro money markets, confidence in them has waned. This is because, the volumes traded have been too low, to possibly reflect a true price. The European Central Bank, has launched its own reference rate, now named the euro short-term rate, abbreviated as ESTER. It is hoped, that ESTER, could eventually serve as a new benchmark.

“This interest rate, which will be produced before 2020, will complement existing benchmark rates, produced by the private sector, and serve as a backstop reference rate,” said the ECB in a statement.