Reversal (Options Arbitrage)
A Reversal is the mirror image of a Conversion — a three-leg options arbitrage strategy in which a trader who is short stock buys a call and sells a put at the same strike and expiration, creating a synthetic long that offsets the short stock and locks in a risk-free profit when put-call parity is violated.
While a conversion captures mispricing when calls are overpriced relative to puts, the reversal (also called a reverse conversion) captures mispricing when puts are overpriced relative to calls. The reversal is assembled by shorting 100 shares of stock, buying one at-the-money call, and selling one at-the-money put with the same strike and expiration.
The long call and short put together create a synthetic long stock position. Combined with the short stock, the net exposure is delta-neutral and entirely hedged. If the stock rises above the strike at expiration, the long call is exercised to buy shares and close the short. If the stock falls below the strike, the short put is assigned and shares are delivered to close the short. Either way, the position unwinds at the strike price.
The profit from a reversal comes from the net credit or debit difference that arises when put-call parity is out of balance. If puts are temporarily overpriced — perhaps due to panicked hedging demand or an unusual short-squeeze scenario — a trader can sell the expensive put, buy the comparatively cheap call, and short the stock to lock in an arbitrage profit as parity normalizes.
Interest rate sensitivity is a key driver of put-call parity violations. When interest rates move rapidly, the implied cost-of-carry embedded in options prices may lag, creating windows for conversions and reversals. Dividend expectations also play a major role: when a special dividend is announced, the put premium surges to reflect the stock price drop on ex-date, and reversals can be set up profitably in the brief window between announcement and market repricing.
In today's markets, algorithmic trading and high-frequency market makers close parity violations in milliseconds, making these trades impractical for retail participants. Understanding reversals is nonetheless valuable because it illuminates how options prices are anchored to each other and to the underlying stock, which helps traders assess whether individual options are fairly valued.
The reversal also plays a conceptual role in synthetic position construction — traders who understand reversals can more easily build synthetic longs and shorts using options when direct stock trading is restricted or undesirable.