Closing Purchase

A closing purchase is an order to buy back an options contract that you had previously sold, in order to exit or reduce that position. It is one of the four basic order types in options trading, alongside opening purchase (buying to start a position), opening sale (selling to start a position), and closing sale (selling to exit a long position).

Here is how it works in practice. Suppose you sold an option earlier — this is called "writing" or "selling to open" — which means you collected a premium and took on an obligation (for example, to deliver shares if the option is exercised against you). That trade left you with a short position in that specific option series (same underlying stock, same strike price, same expiration date). To get out of that obligation before expiration, you place a closing purchase order, often labeled "buy to close" on a broker's trading screen. The premium you pay to buy it back may be more or less than what you originally received, and that difference determines your profit or loss.

The nuance that trips beginners up is distinguishing a closing purchase from an opening purchase. Both are "buy" orders and look identical on a basic order ticket, but they mean opposite things: an opening purchase creates a new long position, while a closing purchase erases an existing short position. Most brokers force you to specify which one you mean (buy to open vs. buy to close) precisely because the market and the clearing house need to know whether you are adding a new contract to your account or cancelling out one you already had. Mixing these up can leave you with an unintended position or a rejected order.

It is also worth noting this is different from simply letting an option expire. A closing purchase is an active, deliberate trade executed in the market at whatever price is currently quoted, whereas expiration is what happens automatically if you do nothing and the contract's date passes.