"Nigh perched with a multiple problem," Burry tweeted, attaching a chart tracking the price-to-sales ratio of the S&P 500 equal-weight index.

As the chart below shows, the ratio was below 1.0 for most of the 1990s and 2000s, but it has nearly doubled over the past decade to more than 2x. While the extreme valuation has been in a downtrend since June 2021, the recent rampage higher in index prices has sent the price-to-sales ratio soaring back towards 2x once again.

This is not the first such warning from the famed investors.

Burry declared in June 2021 that this was the "Greatest Speculative Bubble of All Time in All Things", predicting "the mother of all crashes" that month, and cautioned the market was "dancing on a knife's edge" in February 2021.

At the same time, bond bulls are facing their own crisis of faith as Bloomberg succinctly notes that the last line of defense for the purists has now been reached.

As Carter Worth noted, "the all-data log chart for US 10-Year Treasury Bond yields is the most important trend line of all time, ever, in any and all markets."