A system and method provide price validation for market makers in over the counter (OTC) markets. Specifically, the system compares a new or existing price provided by a market maker with a base rate. If the unilateral difference is less than or equal to a configurable tolerance, the price may be added to validated rates. The unilateral difference is an amount that the new bid source rate is greater than the bid base rate or an amount that the new offer source rate is less than the offer base rate. On the other hand, if the difference is more than the tolerance, the price may be ignored or removed by the system. As a result, the system provides protection against trading on invalid off-market rates or stale rates that is caused by system latency or other types of temporary anomalies.