What is TONA

It is defined as the call rate (weighted average value) for uncollateralized overnight (O/N) call transactions calculated based on the Explanation of “Statistics on Call Market" published by the Bank of Japan.

Quoted from Risk Free Rate Glossary on the Japanese Bankers Association website

Calculation methodology of call rates

The volume-weighted average call rate is the average call rate weighted by the volume of the transactions corresponding to each rate. The rate is calculated by dividing the sum of the product of each transaction volume and the corresponding rate by the sum of the overall transaction volumes, based on data submitted by information providers* (rounded off to three decimal places). The maximum (minimum) rate is the highest (lowest) rate of the maximum (minimum) rates submitted by the information providers.

Quoted from Explanation of "Statistics on Call Money Market" on the Bank of Japan website

Publication time

It will be announced on the Bank of Japan website at the following times.

Provisional results Final results
Call rate Around 5:15pm of that business day (around 6:15pm on the last business days of months except December) Around 10:00am on the following business day
Volumes of uncollateralized overnight call transactions
Amounts outstanding of call transactions

Quoted from Explanation of "Statistics on Call Money Market" on the Bank of Japan website

Risk Free Rate

・Japanese Mega Banks and Trust Banks
・Japanese Regional Banks
・Japanese Second Regional Banks
・Foreign Banks
・Securities Companies
・Asset Managements, etc.

Risk Free Rate

In December 2016, TONA was identified as a risk-free rate (RFR) in the Japanese Yen.
RFR is an interest rate that hardly reflects the credit risk of a bank when it raises funds.

Explanation of "Statistics on Call Money Market"(Bank of Japan Website)
Risk Free Rate Glossary (Japanese Bankers Association website)