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Home > Markets and Payments > SONIA reform

SONIA reform

In July 2015 the Bank announced its plans to reform the SONIA benchmark.  These reforms are anticipated to be fully implemented by April 2018. 
Overall, the reform process will result in:
  • the Bank being the administrator, including the calculation and publication of SONIA;
  • the coverage of SONIA being broadened to include overnight unsecured transactions negotiated bilaterally as well as those arranged via brokers, using the Bank’s Sterling Money Market Data Collection, Form SMMD as data source;
  • the averaging methodology for calculating SONIA changing to a volume-weighted trimmed mean; and
  • reflecting the change in data source and the need to process the greater volume of transactions captured, the publication of SONIA moving to 09:00 on the business day following that to which the rate pertains.
The Bank consulted on its high level proposals for SONIA reform, alongside its proposals for a new sterling money market data collection in 2015, publishing its response to consultation feedback in November 2015.
Further consultations were issued in October 2016 and February 2017, seeking respondents’ views on detailed proposals for the reform of SONIA.
In March 2017 the Bank provided a summary of feedback from the October 2016 and February 2017 consultations, how the Bank has responded and set out the specification of reformed SONIA which will be implemented in March or April 2018.  This also provided an update on the statistical characteristics of reformed SONIA.