What happens to risk premia when monetary policy drives down risk-free interest rates?

The direct effect of an expansionary monetary policy is to drive down risk-free interest rates since central banks essentially buy risk-free bonds. So what is the effect of a fall in risk-free interest rates on risk premia? There are two mechanisms that have opposite effects on risk premia: The "risk channel" of monetary policy: since risk-free interest rates are very low, investors switch to risky assets which drives down risk premia; this is what we are seeing for High Yield corporate bonds and bank bonds; The "caution channel": if investors remain cautious about risky assets, the fall in risk-free interest rates will be offset by a rise in the risk premium, which prevents prices of risky assets from rising; this is what we are seeing for equities. So generally speaking, there is no certainty that an expansionary monetary policy will drive down risk premia.