Position Sizing in a High-Valuation World: Why Most Traders Get Wiped Out

The S&P 500 lost 25% in 2022. The average growth stock lost 60%. The traders who blew up that year were not bad stock pickers. They were running 2015 position sizes in a 2022 valuation regime. With the Shiller CAPE near 39 in 2026, the same mistake is setting up again. The single biggest variable determining whether you survive the next drawdown is position sizing, not stock selection.

Your survival in a high-valuation market is determined by how much you risk per idea, not how good the idea is.

At a Shiller CAPE of 32+, expected 10-year returns are materially lower than they were at CAPE 18-22. That does not mean sit in cash. It means your margin of safety per dollar deployed is thinner, so you need fewer dollars at risk per idea.

Core long-term holdings (60-70%): index funds and blue-chip compounders sized 5-8% each. Add on weakness.

High-conviction individual ideas (15-25%): max 2% per name at entry when CAPE is above 30. Scale in over tranches only if thesis plays out.

Tactical/trading bucket (5-15%): more aggressive on short-term setups, but total bucket risk capped at 4-5% of portfolio worst case.

Cash and short Treasuries (15-25%): currently yielding 4.3-4.7%. Real dry powder, not theater.

If the market is above its 10-year average valuation AND my drawdown exceeds 15% from peak, I automatically reduce new position sizes by 50% until we either get a real reset or I prove the thesis still works with smaller size.

I am not saying go to cash. I am not saying high valuations mean a crash. I am not saying small positions mean you can't make money. I AM saying that the math of starting valuations is real and the sizing rules from 2015 will get you killed in 2026.

Cap loss per idea before you cap upside. Most people do the opposite, they let losers run hoping for recovery and trim winners to "lock in gains." The math punishes that asymmetry over a full cycle.

Read next: Shiller CAPE 39 Math | Why Buy The Dip Is Dangerous

*⚠️ Disclaimer: This post is for educational and entertainment purposes only. MentorSurge is not a financial advisor. Nothing on this site is investment advice. Past performance is not indicative of future results. Position sizing rules are personal and should be adapted to your own risk tolerance, time horizon, and capital. Always do your own research and consult licensed professionals before making decisions with real money.*