Straddle

Definition

A straddle holds a call and a put at the same strike and expiry — long both (long straddle) or short both (short straddle). It is the purest listed expression of a volatility thesis: the long side profits if the underlying moves more than the options priced; the short side profits if it moves less. Direction is irrelevant at entry; magnitude is everything.

How it works / structure

• Legs: ±1 call K, ±1 put K, same expiry, K at the money.
• Long straddle: debit D (= the priced move, opt-expected-move); max loss D at exactly K; breakevens K ± D; unlimited theoretical gain either direction.
• Short straddle: credit C; max gain C at exactly K; breakevens K ± C; UNDEFINED risk both directions — the winged version is strategy-iron-butterfly.
• Parameters (engine-executable): DTE, entry IV gate (iv_rank low for long entries, high for short), event flag (through-event vs clean window changes the thesis — implied_earnings_move_pct), hedged vs unhedged (delta-hedging a straddle isolates realized-vs-implied volatility — mgmt-delta-hedging), exits (mgmt-profit-target, mgmt-time-based-exit, mgmt-stop-loss on the short side).
• Greeks profile: near-zero delta at entry; long straddle = long gamma, long vega, negative theta; short straddle = the mirror.

When it applies

Disagreements with the priced move: long when a bigger move than priced is expected (pre-catalyst with cheap IV), short when the priced move looks exaggerated (post-panic, rich event premium — undefined risk noted). Delta-hedged, it becomes the direct realized-vs-implied volatility trade the platform’s engine can grade cleanly.

Risk profile & failure modes

• Long side, the usual outcome: most windows realize less than priced (see evidence) — the long straddle’s base case is decay; it needs the outlier, and IV crush after events removes the cushion even when direction was right.
• Short side, the outlier ends it: undefined risk both ways; one gap can erase years of collected premium; sizing and wings (strategy-iron-butterfly) are the survival difference.
• Both-breakeven whipsaw: price crossing K repeatedly bleeds the long side’s gamma-scalping opportunity if unhedged, and whipsaws the short side’s defensive management.
• Event-date errors: a straddle bought for an event that moves outside its expiry is pure decay (event-earnings date discipline).

Evidence & limits

Coval and Shumway (2001) documented that zero-beta at-the-money index straddles earned significantly negative average returns — the canonical direct evidence that long volatility costs a premium on average (equivalently, that short volatility collects one, with tail risk). Goyal and Saretto (2009) found a cross-sectional strategy long straddles on stocks with IV far below realized vol earned positive returns in their sample — evidence that the premium’s SIGN can invert when IV is unusually cheap vs history. Both are period-specific with post-publication caveats; per-name event straddle outcomes are the platform’s own recorded evidence (excess_earnings_move_pct).

Falsifiable-thesis examples

Illustrations only, not signals:

• “X’s move by expiry will exceed the straddle-priced move at entry” — falsified by |realized| < priced.
• “Y’s post-earnings straddle value will fall at least 30% the session after the report” — falsified by the repriced straddle.
• “A delta-hedged long straddle on Z will profit this month (realized vol > entry IV)” — falsified by the hedged replay P&L.

Cross-references

• Wider/narrower kin: strategy-strangle (different strikes), strategy-iron-butterfly (short straddle + wings)
• The quantity priced: opt-expected-move, opt-implied-volatility
• Exposures: greek-gamma, greek-vega, greek-theta
• Event mechanics: event-earnings; hedging: mgmt-delta-hedging