In this section
Overview
SONIA (Sterling Overnight Index Average) is an important
We are the administrator for SONIA. That means we take responsibility for its governance and publication every London business day.
SONIA is based on actual transactions and reflects the average of the interest rates that banks pay to borrow sterling overnight from other financial institutions and other institutional investors.
Financial businesses and institutions use SONIA in a variety of ways. For example, to calculate the interest paid on transactions and sterling . SONIA is used to value around £30 trillion of assets each year.
SONIA was selected by the Working Group on Sterling Risk Free Reference Rates as the preferred benchmark for the transition to sterling risk-free rates from Libor.
Our Monetary Policy Committee decides what monetary policy action we take as a central bank. We implement our monetary policy by taking an active role in the financial markets using our Sterling Monetary Framework. SONIA is referenced in over £90 trillion of new transactions each year (based on LCH total volume of OIS cleared swaps during 2020).
SONIA was introduced in March 1997. We took responsibility for it in 2016 and, after consultation, we reformed it in 2018. The way we run SONIA complies with international best practice for financial benchmarks.
How we produce SONIA
We gather data
We check the data is right
We calculate SONIA
We publish it
For more information, see our overview of how we run SONIA.
For information on the calculation methodology for SONIA and the SONIA Compounded Index, see our key features and policies.
If you have any queries about SONIA, please email benchmarkadministration@bankofengland.co.uk.
Historical data
SONIA and the SONIA Compounded Index are freely available on our Interactive Statistical Database by 10am on the business day after it is first published. The database also includes historic data.
To support transparency of the benchmark calculation process, we publish summary information on errors that did not meet our republication criteria.