SONIA

SONIA – Sterling Overnight Index Average
SONIA (Sterling Overnight Index Average) is the key benchmark for overnight interest rates in the United Kingdom. It reflects the volume-weighted average rate at which banks and financial institutions borrow and lend in GBP on an unsecured overnight basis.

Interactive Chart and Historical SONIA Data
The table above is updated daily with the most recent SONIA rate. Click to expand and access the interactive chart showing historical daily values. This allows you to explore overnight market trends, assess volatility, and track how short-term funding conditions in the UK evolve over time.

Administration and Publication
SONIA is administered and published by the Bank of England at around 10:00 CET each business day. The rate is based on actual transactions from the previous day and forms a crucial part of the UK’s monetary and financial framework.

SONIA and/or SONIA Compounded Index data are licensed under the Open Government Licence v3.0 and © the Governor and Company of the Bank of England. The trade marks “Bank of England” and “SONIA” are registered trademarks of the Bank of England.


Frequently Asked Questions about SONIA

What is SONIA?
SONIA is the Sterling Overnight Index Average, a benchmark interest rate that measures the average cost of overnight unsecured lending in British pounds. It is used widely across UK financial markets.

How is SONIA calculated?
SONIA is based on the volume-weighted average of all eligible overnight transactions in the sterling money market. It includes trades conducted by banks and building societies without the use of collateral.

When is SONIA published?
The Bank of England publishes the SONIA rate every business day at approximately 10:00 CET, reflecting activity from the prior business day.

What is SONIA used for?
SONIA is a key benchmark for loans, floating-rate notes, interest rate swaps, and other derivatives. It is also used to calculate compounded interest for risk-free rate products, making it a reliable reference across markets.

How is SONIA different from LIBOR?
Unlike LIBOR, which was based partly on estimates, SONIA is derived entirely from actual transactions. It is more transparent and less susceptible to manipulation, making it a preferred alternative for modern financial contracts.

Where can I view historical SONIA rates?
You can explore historical SONIA values by expanding the table row above and using the interactive chart. It allows you to analyze day-to-day changes and long-term patterns.