Short Put (Naked Put)

Core Thesis

A Naked Short Put sells downside insurance without fully reserving assignment capital. It is a carry strategy that earns theta but loads portfolio left-tail and liquidity risk.

Structure

• Short 1 put at strike $K$ for premium $P_0$.
• Broker margin replaces full cash reserve, introducing financing and liquidation risk.

Expiration Payoff Mathematics

$$\Pi_T = P_0 - \max(K - S_T, 0)$$

• Max profit: $P_0$.
• Break-even: $K - P_0$.
• Tail loss if underlying collapses: up to $K - P_0$ per share.

Risk Profile

• Positive theta and positive delta at entry.
• Negative gamma and short vega are the critical hazards during selloffs.
• Margin requirement can expand procyclically when volatility spikes.

Institutional Guardrails

• Limit gross short-put notional by sector and correlation bucket.
• Stress test gaps (earnings, legal, macro shock) rather than smooth moves.
• Maintain liquidity buffer for margin expansion.

Management Framework

• Take profits early when most extrinsic is harvested.
• Cut or reduce when breach probability rises and skew steepens.
• Roll only with thesis reaffirmation and adjusted sizing.

Failure Modes

• Treating premium as yield without mark-to-market discipline.
• Selling short puts into binary catalysts with insufficient edge.
• Overlapping expiries that create clustered assignment risk.

Practical Checklist

• Can the account withstand a large gap and margin expansion simultaneously?
• Is expected carry superior to defined-risk alternatives (bull put spread)?
• Is downside inventory exposure intentional and sized?