Idiosyncratic risk and market volatility: Threat or opportunity for returns? A study of Borsa Istanbul stocks

This study investigates the relationship between idiosyncratic risk, market volatility, and stock returns for companies traded on the Borsa Istanbul. The analysis calculates idiosyncratic risk and market volatility and estimates the coefficients using cross-sectional and panel data approaches. The GARCH and EGARCH models are used to calculate market volatility, while idiosyncratic risk is measured using the Capital Asset Pricing Model, and three-factor, four-factor, and five-factor models. We run the Fama-MacBeth regression to investigate the cross-sectional relationship between idiosyncratic risk, market volatility, and stock returns and the Arellano-Bover/Blundell-Bond panel regression technique to unveil firm-specific effects. The estimated coefficients demonstrate a positive relationship between idiosyncratic risk and stock returns and a negative relationship between market volatility and stock returns. Furthermore, the findings suggest that larger firm size, higher trading volume, higher market returns, and higher book-to-market ratios have positive effects, while beta and corporate governance indices have negative effects on returns.