The S&P 500 index will experience a market crash of 20% or more from its peak by December 31, 2027.

Resolves YES if the S&P 500 index closes at a level 20% or more below its highest-ever closing price at any point on or before December 31, 2027, using official market closing data. The 20% threshold must be reached on a daily closing price, not just intraday. Resolves NO if no such 20% peak-to-close decline occurs by December 31, 2027.