In Options Trading, What Is the Equivalent of a “Zero-Fee” Transaction and Its Implication?

The closest equivalent is a "commission-free" options trade offered by many modern brokerages. While the commission is zero, the transaction is not truly "free" as costs are often embedded or hidden.

The primary implicit cost is the bid-ask spread, which is the difference between the highest price a buyer is willing to pay and the lowest price a seller is willing to accept. The brokerage may also engage in Payment for Order Flow (PFOF), routing the order to a market maker who profits from the spread, potentially giving the trader a less favorable execution price.

This is the opportunity cost for the trader.