Short-Term WIG20 Volatility around Interest-Rate Decision Announcements by the Monetary Policy Council of the National Bank of Poland: Evidence from 2005–2025

Abstract

This study examines short-term WIG20 volatility around 235 interest-rate announcements by the Monetary Policy Council of the National Bank of Poland in 2005-2025. Volatility is measured from daily log returns in three- and five-day windows and analysed separately for decisions involving interest-rate changes and status quo decisions. Descriptive statistics show generally higher pre-announcement volatility and particularly pronounced skewness and kurtosis before interest-rate-change announcements. Wilcoxon signed-rank and Mann-Whitney U tests show that pre-announcement volatility is significantly higher only for decisions involving interest-rate changes in the three-day window. Between-group differences are also significant in the three-day window, but only at the 10% level.