John Hussman forecasts a correction of -64% dello S&P 500 in the coming years - Hussman Funds

At present, the valuation measures that we find best correlated with actual subsequent S&P 500 total returns are at the most offensive levels in history, matching or eclipsing the 1929 and 2000 extremes. Even considering the level of interest rates, economic growth, and other factors, the S&P 500 currently stands about 2.8 times the level that we believe the index will revisit over the completion of the current market cycle, implying an interim market loss something on the order of -64%. Moreover, the most reliable valuation measures uniformly imply the likelihood of negative total returns in the S&P 500 over the coming 10-12 year period.

Source: Navigating the Speculative Id of Wall Street