What it means
The bid is the price someone offers to pay, and the ask or offer is a price at which someone offers to sell. If the best bid is $10.05 and the best offer is $10.00, the displayed market is crossed by five cents, which is different from a locked market, where both prices are equal.
The best bid and offer summarise a set of quotes at a given moment, so a trader examining a cross needs to know whether those quotes were displayed through the same data feed, at what times they arrived and whether they were protected quotations, which is a separate inquiry from deciding which trading rule applies to a specific venue. A screen can show a cross when quotes from multiple venues arrive at different times, and one side might have been cancelled before a trader could act.
Consolidated market data, venue timestamps and feed latency can explain an apparent opportunity that never existed simultaneously. Crossed quotes can appear around market opens, halts or rapid price moves, and a consolidated feed may lag a venue's latest update, so compare source timestamps and trade prints before using the event in an execution-quality report.
Displayed price is not the whole trade, because a quote can have limited size, access conditions or fees. An order for 10,000 shares cannot assume that a 100-share displayed offer is available for the full amount at the same price.
Markets also distinguish firm and non-firm quotations, so a stale or non-executable indication should not be treated as a certain offer, and a trading desk checks the actual venue and order book rather than calculating profit from two numbers in isolation. A genuinely executable bid above an offer could attract fast trading that buys at the lower price and sells at the higher one, so the cross may close almost immediately.
Speed, costs, routing and settlement affect whether a trader can capture any spread. A crossed market is not a negative bid-ask spread that persists as a stable customer price, since it can be an ephemeral market-data state during volatility, and the best bid and offer may come from different venues with different access and order sizes.
Some venues have rules intended to prevent locked or crossed quotations, and rules differ across market types and times, including opening or special sessions. A manager should seek compliance review before inferring that a crossed screen proves misconduct.
Analysts evaluating a broker should separate crossed quote time from realised execution, since a customer who paid a higher price than a stale offer did not necessarily miss a trade, and they should verify whether the offer was protected, accessible and available at the order's relevant time. A crossed market differs from a cross trade.
A cross trade matches a buy and sell order between accounts under a transaction process, while a crossed market describes the relationship between displayed bid and offer quotations, whether or not those orders actually trade against each other.
In practice
Real-world examples.
Example
A quote feed shows $10.05 bid and $10.00 offer for the same stock. The desk verifies venue timestamps and accessible sizes before labelling the five-cent difference an opportunity.
Example
An old ask remains on one dashboard after the venue cancels it. A later bid appears higher, but the two quotes were not simultaneously executable.
Example
A broker reviews a client's order during a fast market. It compares protected, accessible quotes at the actual order time rather than relying on a screenshot taken seconds later.
Formula
Calculation
Displayed cross amount = best bid - best offer when positive. A $10.05 bid minus a $10.00 offer yields a five-cent displayed cross. This is not a guaranteed five-cent profit: share size, simultaneous availability, fees and routing can erase it.Case study
Seen in the real world.
Fictional case: A surveillance team flags repeated crossed quotes during a volatile open. The analyst joins venue timestamps, sizes, cancellations and trade prints. Most apparent crosses came from a delayed data feed; one brief cross was real but inaccessible to its client under the relevant routing conditions. The team fixes the feed display and documents the execution review without alleging misconduct from the screenshot alone.
Watch out
Common mistakes.
- Treating an asynchronous screen cross as a guaranteed risk-free trade.
- Ignoring displayed size, fees and venue access when comparing bid and offer.
- Confusing a crossed market quotation with a cross trade between managed accounts.
Questions
People also ask.
How is a crossed market different from a locked market?
In a cross, best bid exceeds best offer; in a lock, they are equal.
Does a cross guarantee arbitrage profit?
No. Quotes may be stale, inaccessible or too small, and execution costs matter.
Is a crossed quote proof of a rule violation?
No. Check the applicable venue rules, data timing and actual order behaviour before reaching that conclusion.
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