OECD countries: What happens when investors worry about asset price bubbles?

The very expansionary monetary policy in OECD countries is driving up asset prices (equities, real estate). But even though , in theory , asset prices are likely to rise further, investors will at a certain stage be concerned about their high level and stop buying them. We should then see an increase in cash holdings, as investors wait for asset prices to correct downwards before buy ing again. Asset prices are now lower than what the very low level of interest rates should imply, but investors are nevertheless not fleeing to cash.