A purchase can fill the requested quantity while crediting fewer units if commission is deducted from the acquired asset. Other differences can come from partial execution or reservations. Trace the order, fee entries and balance movements separately, then calculate unit cost using the actual net quantity without counting the same fee twice.
An asset can appear in an exchange account while part of it is unavailable for withdrawal because an open order reserves it. That is only one possible explanation. Reconcile the order quantities and fills first, then check funding holds, product obligations and withdrawal requirements instead of canceling instructions at random.
An order can be rejected despite sufficient funds because its quantity, price, value or supported options do not satisfy the market’s rules. Record the exact rejection before changing anything. These hypothetical examples separate the checks so a precision error does not lead to an unintended larger purchase.
Immediate-or-cancel and fill-or-kill specify what happens when an order cannot be completed immediately under its conditions. IOC can accept a partial execution and end the remainder; FOK requires the whole quantity immediately or no execution. Neither instruction selects a suitable price or guarantees the response will reach your device.
Good-till-canceled is a time-in-force instruction operating within a market’s rules. A GTC order can remain active after you close the app or change your plan. To manage it, track the quantity already filled, the active remainder and the balance still reserved before canceling or replacing anything.