GPW Benchmark, as the benchmark administrator, informs that public consultations on the algorithmic method used to determine the WIBOR for the 1Y Fixing Tenor during its run-off period has been finalized.

During the period of obligation imposed on the Administrator by the Polish Financial Supervision Authority (KNF) to continue publication of the WIBOR for 1Y Fixing Tenor, i.e. starting from December 22, 2025 till December 21, 2026, the WIBOR for 1Y Fixing Tenor will be determined with the use of an algorithmic method that is based on the WIBOR for the 3M Fixing Tenor, adjusted by an adjustment spread determined using the dynamic adjustment spread method. The consultation participants also indicated that the calibration period for the correction coefficient used within the dynamic adjustment spread method should be the 5-year period, i.e. October 2020 - September 2025. Such calibration assures relatively smaller volatility of the determined rate and its better long-term goodness of fit to the historical values of the WIBOR for 1Y Fixing Tenor (value of correction coefficient under the 5-year calibration is 0.57).

Starting from December 22, 2025, each day during the run-off period, the WIBOR for 1Y Fixing Tenor will be determined based on the value of the WIBOR for 3M Fixing Tenor for a given day, which is in order to ensure matching the current market situation increased by the difference between the WIBOR for 6M Fixing Tenor on that day and the WIBOR for 3M Fixing Tenor for that day, multiplied by the number 3, which is used as an adjustment aimed at removing the impact of the difference between the distance between the 1Y and 3M Fixing Tenors (9 months) and the distance between the 6M and 3M Fixing Tenors (3 months), and further multiplied by the fixed correction coefficient determined through consultations at 0.57, which ensures optimal fit to the historical values of the WIBOR for the 1Y Fixing Tenor. The inclusion of the correction coefficient of 0.57 in the method allows for long-term minimization of differences between historical values of the WIBOR for the 1Y

Fixing Tenor and the values of the index determined using the dynamic adjustment spread method. The method is presented in the following formula:

WIBOR for the 1Y Fixing Tenor = WIBOR for the 3M Fixing Tenor + 1.71*(WIBOR for the 6M Fixing Tenor - WIBOR for the 3M Fixing Tenor)

The value of 1.71 in the above formula is a result of multiplying the correction coefficient of 0.57 by 3.

The summary of the consultations is available on the Administrator's website in the section dedicated to interest rate indices in the "Consultations & Analyses" tab.