Out of 44 developed and emerging markets in the world, the US stock market is the most expensive on a 10 Year PE ratio basis with a value of 25 (CAPE). If you include frontier markets, the US is the most expensive out of 55 markets with the one exception of Sri Lanka.
Now, the US isn’t in a bubble, nor does this mean it must crash or even go down. What it does mean, is that the rest of the world is much cheaper and US returns should be muted for the next 5-10 years. AND it means the biggest weighting in all of the global market cap portfolios (50%) is the most expensive market. Be forewarned!