The South African Rand Overnight Index Average (ZARONIA) reflects the interest rate at which rand-denominated overnight wholesale funds are obtained by commercial banks. It is based on actual transactions and calculated as a trimmed, volume-weighted mean of interest rates paid on eligible unsecured overnight deposits.

On 2 November 2022, the SARB commenced publishing ZARONIA primarily to allow market participants to observe its performance and consider the implications of adopting it as a replacement for the Johannesburg Interbank Average Rate (Jibar). The observation period ended on 3 November 2023. Certain observation period statistics have been restated to reflect revisions that were processed post their publication. Market participants may use ZARONIA as a reference rate in financial contracts.

The Market Practitioners Group has designated ZARONIA as the successor rate to replace Jibar.

ZARONIA is published every South African business day at 10:00. The benchmark rate may be republished at any time before 12:00 in the event that an error is discovered after the standard publication of the benchmark at 10:00. The calculation methodology and policies governing ZARONIA are prescribed in the Technical Specification Paper.

Interest rate benchmark data
Interest rate benchmarks graph

The South African Reserve Bank (SARB), in so far as it contributes to the determination process of the rates it publishes, takes reasonable measures to ensure the accuracy of the rates. The SARB shall not be liable for any error or inaccuracy in the rate or the information, for any delay in updating the rate or the information, nor shall it be liable or responsible for any reliance on, use of, or inability to use the rate or the information in any commercial activity. The SARB makes no representations or warranties, expressed or implied, as to the rates’ accuracy, timeliness, completeness, merchantability, or fitness for any particular purpose. The SARB accepts no liability or responsibility for any direct or indirect loss, damage, expense, or claim howsoever arising, including but not limited to any such loss or claims which may arise from any act, commission, or omission (negligent or otherwise) on the part of the SARB, its employees and representatives relating to, or in connection with the calculation and/or publishing, or delay in the publishing or republishing of a reference rate, or from the direct or indirect reliance on, use of, or inability to use a rate.