SONIA

Interest rate benchmarks.

Sterling Overnight Index Average.

Tracks actual average market sterling funding rates each day:

for settlement that day
where repayment is made on the following business day.

It is defined and calculated as the weighted average rate (to four decimal places) of all unsecured sterling overnight cash transactions brokered in London by EVIA* member firms between midnight and 4.15pm London time with all counterparties in a minimum deal size of £25 million.

The Bank of England assumed responsibility as the administrator of a revised SONIA with effect from April 2018.

Among other changes, SONIA was broadened to include overnight unsecured transactions negotiated bilaterally, as well as those arranged via brokers.