# Spread Widening > A transient expansion of the bid-ask spread beyond its typical range, most commonly around scheduled news releases, liquidity transitions, and session rollovers. - Canonical: https://hadalinstruments.com/glossary/spread-widening/ - Term set: https://hadalinstruments.com/glossary/ --- Spread widening is, in itself, legitimate microstructure. A market maker quoting a two-sided price is short an option to every better-informed counterparty; when a scheduled release is seconds away, the probability of being run over by informed or simply faster flow spikes, and the rational response is to quote wider or withdraw. Liquidity thins, the touch widens, and fills degrade — at every venue, for every participant. The institutional market is not exempt. The measurement question that matters is not *whether* spreads widen but *how a specific venue's widening compares to the market's*. Three properties characterise a widening profile: magnitude (how many multiples of the baseline spread), duration (how long until the spread renormalises), and timing (whether widening anticipates the event, tracks it, or persists suspiciously after underlying liquidity has returned). Comparing one broker's profile against a multi-venue reference at the same timestamps separates market-wide widening, which is physics, from venue-specific widening, which is policy. The retail relevance is blunt. Advertised "typical" spreads are averages sampled predominantly in calm regimes, but retail order flow does not arrive uniformly across regimes: stops and pending orders cluster precisely around the events where spreads are widest, so the spread a trader's orders actually experience can differ materially from the spread the marketing page reports. A backtest fed the advertised average inherits the same optimism — one of the quieter routes into [backtest overfitting](/glossary/backtest-overfitting/) via understated [execution cost](/glossary/execution-cost/). Spread widening also interacts with feed integrity: a venue can disguise widening by throttling or suppressing ticks during the event window, which is the territory of [censoring](/glossary/censoring/) and [quote staleness](/glossary/quote-staleness/). The [Broker Feed Auditor](/instruments/broker-feed-auditor/) I am building is intended to measure widening profiles from recorded feeds rather than assert them. ## Commonly confused with Neighbouring concepts that get used interchangeably, and the distinction that actually separates them. - **[Spread regime](https://hadalinstruments.com/glossary/spread-regime/)** — A regime is the prevailing state a spread sits in for a stretch of time. Widening is a transient excursion out of it. Confusing the two turns a temporary event into a description of the instrument, or hides an event inside an average that never noticed it. - **[Slippage](https://hadalinstruments.com/glossary/slippage/)** — Widening changes the cost quoted to you before you act, which you can still decline. Slippage is the divergence between the price you expected and the one you received. During an event you are usually paying both, which is why attributing the whole cost to either one understates it. - **[Liquidity void](https://hadalinstruments.com/glossary/liquidity-void/)** — A void is depth absent behind the touch; widening is the touch itself expanding. They frequently occur together and are not the same measurement — a spread can widen with depth intact, and depth can evaporate while the quoted spread looks ordinary. - **[Censoring](https://hadalinstruments.com/glossary/censoring/)** — Widening is what the feed reports. Censoring is what the feed omits — a venue that throttles or suppresses ticks during the event window can present a narrower spread than the one it was actually quoting. The second is a claim about the record rather than about the market. ## How to measure it in your own data A definition you cannot test is a definition you have to take on trust. This is the shortest honest route from the concept to a number you computed yourself. - **Records you need** — Timestamped bid and ask from your own venue, the same series from a multi-venue reference over the same timestamps, and a calendar of scheduled events. The reference is not optional — without it you can describe a widening but you cannot attribute it. - **What you compute** — Three properties, computed per event window: magnitude, as multiples of that instrument's baseline spread; duration, from onset until the spread renormalises; and timing, meaning whether the widening anticipates the event, tracks it, or persists after it. Then run the same three against the reference. - **What the answer tells you** — Widening that matches the reference is market-wide, and market-wide widening is physics — a maker quoting two-sided prices into an imminent release is short an option to anyone faster or better informed. Widening that exceeds the reference in magnitude, or persists after underlying liquidity has returned, is venue policy rather than market condition. The persistence case is usually the most informative and the least examined. ## Questions and answers ### Does spread widening mean my broker is cheating me? By itself, no — it is legitimate microstructure, and it happens at every venue for every participant when a scheduled release is imminent. The question worth asking is comparative: how does this venue's widening profile compare with a multi-venue reference at the same timestamps. Market-wide widening is physics; the excess over it is policy. ### Why is the spread I actually pay worse than the advertised typical spread? Because advertised averages are sampled predominantly in calm conditions, while retail order flow is not uniformly distributed across conditions. Stops and pending orders cluster around exactly the events where spreads are widest, so the spread your orders meet can differ materially from the one on the marketing page without the marketing page being false. ### How does spread widening affect a backtest? Spread widening is one of the quieter routes to an over-optimistic result. A simulation fed the advertised average inherits its calm-regime bias, and every stop triggered during an event pays the event regime rather than the average. The strategy does not need to be wrong for the backtest to be — the cost assumption is enough. ### Can a venue hide how much it widened? The measurement depends on the feed, and a feed can be throttled or suppressed during the window that matters. That is why widening and feed integrity are the same investigation: a spread series with gaps in it during the exact minutes under examination is a finding about the record before it is a finding about the spread. ## If this has already cost you Whether a venue widened more than the market did is answerable by comparing the same timestamps against a reference feed. - [Feed Fidelity Assay](https://hadalinstruments.com/assays/#feed-fidelity-assay) “Is the feed my terminal shows me behaving consistently?” Will not establish: A verdict on your broker. One exported log from one terminal measures your feed as you received it — venue-side behaviour, other account tiers and intent are all outside what this data can carry. - [Outage-Window Report](https://hadalinstruments.com/assays/#outage-window-report) “What did the platform outage actually cost me?” Will not establish: What you would have done. A counterfactual is bounded, not known — the report states the range the reference market offered, not the exit you would have taken, and whether the window’s cost is anyone’s liability is a question for the firm or your adviser, with the measurement in hand. Intake is not open yet, so none of these can be commissioned today. They are listed here so you know the measurement exists and what it would and would not settle — the [launch list](https://hadalinstruments.com/pricing/#waitlist) hears first. ## Work it out yourself Free calculators that take this concept as an input. Each shows its working, so the number it gives you can be checked rather than taken on trust. - [Pip value calculator](https://hadalinstruments.com/tools/pip-value-calculator/) One pip per lot, and at your size · The conventions, stated and editable - [Forex profit calculator](https://hadalinstruments.com/tools/forex-profit-calculator/) Net result, costs included · Gross — the other calculators’ figure ## Related terms Derived from the links this entry makes and the entries that link back to it. - [Adverse Selection](https://hadalinstruments.com/glossary/adverse-selection/) The systematic tendency to transact precisely when the counterparty knows something you do not — filled when the market is about to move against you, missed when it would have moved in your favour. - [Backtest Overfitting](https://hadalinstruments.com/glossary/backtest-overfitting/) The condition in which a strategy's historical performance reflects fitting to noise in a particular dataset rather than a persistent market effect, so that live performance regresses toward zero or below. - [Censoring](https://hadalinstruments.com/glossary/censoring/) The thinning of a price feed — updates dropped, coalesced or rate-limited — during the intervals in which the underlying market is moving fastest, so that the record understates the spread widening and depth withdrawal that actually occurred. - [Execution Cost](https://hadalinstruments.com/glossary/execution-cost/) The total cost of converting a trading decision into a position — spread, commissions and fees, slippage, market impact, financing, and the opportunity cost of orders that were rejected or never filled. - [Liquidity Provider](https://hadalinstruments.com/glossary/liquidity-provider/) A participant that quotes two-sided prices and stands ready to trade against incoming orders, compensated by the spread for carrying inventory risk and adverse-selection risk. - [Liquidity Void](https://hadalinstruments.com/glossary/liquidity-void/) A moment in which resting orders are withdrawn faster than they are replaced, leaving stretches of the price axis with nothing to trade against, so that price traverses them in near-vertical jumps. - [Non-Farm Payrolls (NFP)](https://hadalinstruments.com/glossary/non-farm-payrolls/) The monthly US employment release — published by the Bureau of Labor Statistics, typically at 8:30 a.m. Eastern on the first Friday of the month — which functions as the largest recurring scheduled volatility event in foreign exchange. - [Quote Staleness](https://hadalinstruments.com/glossary/quote-staleness/) The age of a displayed quote relative to the current state of the market it claims to represent; a stale quote advertises a price that is no longer executable. ## Where the term is used Instrument pages whose published copy uses this term. Each page states what it measures and what it does not establish. - [Stress Harness](https://hadalinstruments.com/instruments/stress-harness/) What would 2015-01-15 do to your book today? Desk Discipline ## In the research Spread Widening comes up in four research notes on this site, and this entry lists three of them. - [How much does the range actually widen at NFP?](https://hadalinstruments.com/research/the-nfp-range/) What 1,820 scheduled-release windows across 28 pairs were measured for — and why the range-expansion factors stay unpublished until their artifact ships. - [Is my broker's feed honest? How to test it](https://hadalinstruments.com/research/is-my-brokers-feed-honest/) Honest is a comparison, and retail traders have nothing to compare against. Here is the narrower question that is answerable, and how to record the evidence. - [Why is my live spread wider than my backtest?](https://hadalinstruments.com/research/why-is-my-live-spread-wider-than-my-backtest/) Usually because the backtest used a spread that never existed. Here is how to find which of the four causes is yours, and what each one costs you. ## Cite This Definition APA BibTeX HTML Hadal Instruments. (2026). Spread Widening. Hadal Glossary. https://hadalinstruments.com/glossary/spread-widening/ Version 2b360a7, 2026-08-28. @misc{hadal_2026_spread-widening, author = {Hadal Instruments}, title = {Spread Widening}, year = {2026}, url = {https://hadalinstruments.com/glossary/spread-widening/}, howpublished = {Hadal Glossary}, version = {2b360a7}, note = {Pre-launch publication; version dated 2026-08-28} } Source: Hadal Instruments, Spread Widening. Original Research Copy Citation **Version 2b360a7** identifies the commit that last changed this page in Hadal's content repository. That repository is not public, so the identifier does not resolve externally — it is published so a citation pins one specific state rather than a moving page. To obtain the exact version cited, use the [press and research route](https://hadalinstruments.com/press/).