These are the six factors that Ray Dalio analyses when it comes to a bubble in the stock market:

1. How high are prices relative to traditional measures?
2. Are prices discounting unsustainable conditions?
3. How many new buyers (i.e., those who weren’t previously in the market) have entered the market?
4. How broadly bullish is sentiment?
5. Are purchases being financed by high leverage?
6. Have buyers made exceptionally extended forward purchases (e.g., built inventory, contracted forward purchases, etc.) to speculate or protect themselves against future price gains?