The Bank of England has confirmed that it has implemented its reforms to the SONIA interest rate benchmark. SONIA, the Sterling Overnight Interbank Average Rate, which has been administered since April 2016 by the BoE, is the existing unsecured reference rate for the sterling Overnight Indexed Swap market.

The BOE announced in October 2017 that the methodology for calculating SONIA would move from being based on a market for brokered deposits (which has limited transaction volumes) to a methodology involving a volume-weighted trimmed mean. The BOE has also separately published the key features and policies for SONIA, which summarize how SONIA is calculated and administered, including the governance arrangements. The BoE intends to publish an assessment of the benchmark's compliance with the International Organization of Securities Commissions' Principles for Financial Benchmarks in Summer 2018.

View the BoE press release.

View the SONIA key features and policies document.