We develop an Arbitrage Pricing Theory framework extension to study the pricing of squared returns/volatilities. We analyze the interplay between factors at the return level and those in idiosyncratic variances. We confirm the presence of a common idiosyncratic variance factor, but do not find...

Time-varying leverage driven by common shocks to firm asset returns introduces a factor structure in idiosyncratic equity return volatilities (IVOL). In a standard dynamic capital structure model in which the CAPM holds for asset returns, we show that three factors explain the IVOL...