A synthetic position uses options (and sometimes stock) to replicate the payoff of a different instrument — like a synthetic long stock made from a call and a put. It’s a consequence of put-call parity.

How synthetics work

Because put-call parity links calls, puts, and the underlying, you can combine them to replicate another payoff. Synthetic long stock = long call + short put (same strike) — it behaves like owning the stock. Synthetic long call = long stock + long put. Each “synthetic” matches the payoff of the thing it replicates, built from different pieces.

Why they exist

Synthetics let traders create exposures more cheaply or with less capital, exploit arbitrage when parity is off, or construct positions a single instrument can’t. They’re a professional/arbitrage tool, showing how flexible options are — you can rebuild almost any payoff from calls, puts, and stock.

A synthetic rebuilds one instrument’s payoff from others — long call + short put is long stock. Options are Lego; synthetics are what you build.

The takeaway

Synthetic positions replicate one instrument’s payoff using others, rooted in put-call parity. They’re advanced/arbitrage concepts (conversions and reversals are synthetic arbitrage), not scalping tools — but they deepen your understanding of how options relate to each other and the underlying.