Put-Write as Systematic Strategy
A put-write strategy systematically sells put options on an equity index—in this case, the S&P 500—and collects premium income. The economic intuition is straightforward: put buyers are purchasing downside protection (insurance), and put sellers are providing that insurance. The insurance premium is the strategy’s return.
The key parameter is strike selection. Selling at-the-money puts provides maximum premium but maximum downside exposure. Selling out-of-the-money puts reduces both premium and risk. The optimal strike depends on the investor’s view of the implied-realized volatility gap and their loss tolerance.
Strike Selection Parameterization
The analysis tests six strike selection rules, parameterized by the current spot price $S_0$, historical volatility (hv), and VIX:
| Strike Rule | Annual Return (2010-2018) | Total Return |
|---|---|---|
| 0.90 · S₀ | 1.98% | 19.29% |
| 0.93 · S₀ | 6.94% | 83.08% |
| 0.95 · S₀ | 8.76% | 113.11% |
| 0.98 · S₀ | 24.16% | 602.26% |
| (1 − 0.4v) · S₀ | 16.99% | 310.97% |
| (1 − 0.1h) · S₀ | 15.37% | 262.63% |
The VIX-adjusted strike rule—setting the strike at $(1 - 0.4v) \cdot S_0$ where $v$ is the current VIX level—dynamically adjusts to the market’s risk pricing. When VIX is high (fear is elevated), the strike moves further out-of-the-money, providing more protection while still capturing elevated premiums.
The 2018 Catastrophe
2018 exposed the embedded tail risk. All six strategies suffered severe losses, ranging from −30% to −57% across variants. The “10% + 2%” exit strategy (close positions at 10% loss, with actual realized loss of 12%) limited the damage but did not prevent it.
The losses occurred primarily during the February 2018 “Volmageddon” event, when the VIX spiked from ~13 to over 50 in a single trading session. Short volatility strategies across the market experienced simultaneous forced liquidations, creating a self-reinforcing feedback loop that amplified the initial move.
Eight years of accumulated premium can be erased in a single week. The risk is not that the strategy fails—it is that the strategy succeeds for long enough to create overconfidence.
Risk Management Architecture
The put-write case study establishes critical risk management principles:
- Exit strategies are essential but insufficient. The “10% + 2%” rule limits individual-month losses but cannot prevent catastrophic drawdowns in gap-down scenarios.
- VIX-adjusted sizing is structurally superior to fixed-percentage strikes. The $(1 - 0.4v)$ parameterization automatically reduces exposure when the market prices risk higher.
- Annual returns of 24% in a put-write strategy indicate excessive risk, not superior alpha. The 0.98$S_0$ strike (highest return) had the worst 2018 drawdown—the return and risk were two sides of the same position.
- 2-month expiry variants provide more frequent rolling opportunities and the ability to reposition mid-crisis, but also higher transaction costs and more active management requirements.
Derived from From Equations to Capital research program, by Mourad E. Mazouni, PhD, PMP. View Volume I →