What "voided" means
Voiding a trade means the broker cancels or re-prices a fill after the fact, so the trade is removed or adjusted as if it happened at a different price. It is rare and should always come with a clear explanation, usually referencing a specific clause in the terms.
Legitimate reasons it can happen
A clear pricing error — an 'off-market' or erroneous quote where the fill was at an obviously wrong price, which many terms allow to be corrected. A technical fault or feed glitch that produced a bad tick. Trades that breach specific rules in the client agreement. These corrections, done transparently and consistently, are generally within the terms.
When it is a red flag
Voiding only your winning trades while leaving losers, vague or shifting explanations, no reference to any term, or a pattern of cancelling profitable trades — these suggest unfair treatment rather than genuine error correction. A broker that voids selectively is one to be very wary of.
What to do
Ask for the exact reason and the specific clause in writing. Compare the fill price against an independent price source to see whether it truly was erroneous. Keep screenshots and the trade history. If the explanation does not hold up, complain in writing and, if the broker is regulated, escalate to the regulator.
Broker's fault or yours?
Correcting a genuine, documented pricing error can be legitimate. Selective or unexplained voiding is a serious problem on the broker's side and a strong reason to move your money, since it undermines the fairness of every trade you place.