This is a simple mean-reversion bet. As you can see, it's rare for the index to go more than 800 days without revisiting this long-term trendline. There's nothing special about the trendline, it's just a moderately aggressive rate of price appreciation that fits the log chart pretty well.

I would trade this idea by purchasing a SPY 455 Put with April 2025 expiration.

SPX ES1! SPY
Chart PatternsTrend Analysis

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