SONIA sterling overnight index average

Source: Bank of England Statistical Database, series IUDSOIA (SONIA). Licence: SONIA data licensed under the Open Government Licence v3.0 and copyright the Governor and Company of the Bank of England. The trade marks “Bank of England” and “SONIA” are registered trade marks of the Bank of England (terms). Files: data/raw/boe-sonia.csv.

Reading this series

SONIA is the sterling overnight index average, the risk-free reference rate for sterling and the benchmark that replaced LIBOR in that role. The Bank of England publishes it from transaction data, but it does not set it: it is a market rate reflecting unsecured overnight borrowing. This page uses Bank of England series IUDSOIA, under the Open Government Licence, with history from 1997 that includes the 2018 reform of the benchmark.

Because it is a market rate, SONIA moves daily and is not stepped. The headline is the latest daily print; the chart and the long-run statistics use month-ends, which keeps the drawn series readable. Read the value with its as-of date, then the "versus the previous reading" line for the most recent change. Mean, median, low and high summarise the observations in this build, not an official average. Chart and Table present one series two ways, range buttons filter the window, and Explore loads zoom and pan only when asked. SONIA is not Bank Rate, and it is not a mortgage or savings rate.

About this desk

The United Kingdom desk leads with Bank Rate, the Bank of England's policy rate, then SONIA, the sterling overnight market benchmark the Bank publishes but does not set. Euro-area, US, Canadian and Australian rates follow, with the rest of the build's series after them. All desks republish the same official series; this desk only reorders the menu and the wording, so the figures do not change when you switch desks.

Both UK series come from Bank of England statistical tables and are republished under the Bank's open-data terms, with attribution. Bank Rate is a policy setting that moves at MPC decisions; SONIA is a transaction-based market rate that moves daily. The build does not publish a UK retail mortgage or savings rate, because no such official series is ingested here — those pages are absent rather than estimated. This is not financial advice.