Synthetic Short¶
A synthetic short is a two-leg options position constructed by buying one put and selling one call at the same strike price and expiration date. The combined position replicates the profit and loss profile of shorting 100 shares of the underlying stock, with a net delta of approximately -1.00. It is grounded in put-call parity, which holds that a long put plus a short call at the same strike and expiration is economically equivalent to a short stock position.
HOW IT WORKS¶
The position is entered by buying one put at strike K and selling one call at the same strike K and expiration T. The net premium is the difference between the call premium and the put premium. If the call is more expensive, the position opens for a credit; if the put is more expensive, it opens for a debit. The breakeven at expiration equals the strike price adjusted by the net premium. Profit is theoretically unlimited to the downside as the stock falls toward zero, and loss is theoretically unlimited to the upside since the short call has no ceiling. Net theta is negative — the long put decays daily while the short call gains — so the position loses value over time if the stock does not move. Assignment risk on the short call is also a factor, particularly around dividend dates.
IN TAPEBOARD¶
In the Tapeboard terminal, synthetic shorts appear in the positions table as a two-leg spread with a combined delta display near -1.00. The P&L chart overlays the synthetic payoff against an equivalent short stock position so traders can compare the two side by side, including the drag from net premium paid or received. Tapeboard flags assignment risk on the short call leg and displays daily theta bleed at the position level. Traders building a synthetic short from an existing long call can use the leg-add tool to attach the short put at the matching strike without closing the original position.