A binary payoff has a defined contractual outcome, but an order to acquire it can still execute in pieces. If a planned position requires two complementary legs, different executed quantities can leave a directional exposure that the original plan did not contain.
Work from the quantities actually filled
The calculation below assumes an illustrative order-book product with complementary yes and no outcomes, each paying USD1 if its condition is satisfied and zero otherwise. It excludes fees, financing and exceptional settlement provisions. It is a mathematical example rather than an available product or trading recommendation.
Suppose an intended position involves 100 yes contracts at USD0.42 each and 100 no contracts at USD0.55 each. Before that intended position is completed, only 60 yes contracts and 40 no contracts execute. The cash paid is USD25.20 for yes and USD22.00 for no, or USD47.20 in total.
If yes wins under the assumed settlement, the receipt is USD60 and the resulting profit is USD12.80 before costs. If no wins, the receipt is USD40 and the loss is USD7.20. The asymmetry comes from the 20 unmatched yes contracts. A screen showing both order tickets would be insufficient evidence that the intended quantities were acquired.
This example separates an execution problem from a forecast. No probability estimate is required to identify the different cash outcomes. The relevant inputs are the actual quantities, fill prices and contractual receipts.
An unfilled remainder needs its own state
CME Group's audit-trail test for Fill and Kill orders explicitly includes submission, acknowledgement, a partial-fill notice and an elimination notice. It provides an exchange-documented example of why order acceptance, executed quantity and the removal of a remainder are separate recorded events. That test concerns CME's stated order-entry environment; it does not establish the order types available on every binary venue. CME Group — AutoCert+ audit trail: Fill and Kill orders ↗
CME's iLink execution-report documentation likewise distinguishes order status from the event reported. Its Trade Outright message includes total filled quantity, quantity still open for execution and the quantity of the reported fill. These fields describe its documented protocol and provide a concrete example of the records needed to reconstruct an order. CME Group Client Systems Wiki — iLink Execution Report: Trade Outright ↗
For a particular product, the venue's own rules decide whether an order can rest, partially fill, expire or use a supported quantity condition. The general labels need to be checked against those actual rules before they become assumptions in a risk calculation.
Reconcile each leg before describing the portfolio
A useful position record connects the original instruction with all fills, their prices, any cancellation acknowledgement and the final outstanding remainder. Each leg needs its own record. Adding a second order without confirming the first leg's remaining state can change the exposure again.
For a customer explanation or performance report, the portfolio should therefore be reconstructed from executions rather than intended orders. In the example, the correct description is 60 yes and 40 no, with its asymmetric payoff. Preserving that factual execution state makes the source of the risk visible and keeps a partially completed plan from being reported as a completed position.