Market Measures - November 14, 2025 - What Makes BPR a Reliable Risk Gauge

The market measure segment explored how buying power serves as a reliable risk gauge for undefined risk positions. Using SPY strangles as a study case over five years (2020-2025), the analysis showed that buying power effectively quantifies potential risk exposure. Research indicates a mere 0.1% chance that losses exceed the buying power reduction on trade entry. Three key drivers of buying power—price, delta, and implied volatility, create a dynamic risk assessment tool. Higher deltas and underlying prices increase buying power requirements linearly, while implied volatility has an inverse relationship. The 10-20 delta range offers optimal risk-reward. When volatility spikes, traders should defensively reduce position sizes and maintain cash reserves for potential opportunities. For those concerned about undefined risk, turning naked positions into spreads can significantly reduce buying power requirements while maintaining strategic exposure.