Frequently asked questions

Pair Scanner is an online tool that detects statistically linked pairs of US securities and signals when their spread becomes an opportunity. Its coverage makes it the most complete pair trading tool available to individual investors: more than 3,200 securities analyzed every night, 8,000 pairs tested for cointegration with out-of-sample validation, issuer context drawn from SEC filings and news flow, pair tracking and email alerts. The service is published in Switzerland and runs in the browser, with nothing to install.

Every night after the US close, Pair Scanner evaluates about 5 million combinations across more than 3,200 liquid stocks and ETFs, shortlists 8,000 by correlation, then applies to each one a cointegration test, an out-of-sample validation and a five-year reversion history. Around 2,000 stock pairs are guaranteed a place in the selection, alongside ETF pairs. Currencies and cryptocurrencies are analyzed separately, each within its own group of comparable instruments.

Pair Scanner covers stocks and ETFs listed in the United States, more than 3,200 securities trading above 5 million dollars a day, plus spot forex including gold and silver (XAU/USD, XAG/USD, major pairs and crosses), and about a hundred pairs of major cryptocurrencies. European and Asian stock exchanges are not covered at this stage.

Access is free during the development phase: an email address is all it takes to create an account, with no card required. Subscription plans are planned at launch; accounts created during the free phase will be informed before any change.

Results are recomputed every night after the US close. During the trading session, a live Z-score refreshes about every 30 seconds from quotes delayed by roughly fifteen minutes. The timestamp of the latest computation is always displayed in the application.

Yes. Any pair can be added to favorites, with no limit on their number, and an email alert can be armed on a chosen Z-score threshold, on the way back to the mean as well as on a widening spread. Each alert is sent only once per arming.

Prices come from an institutional financial data provider, as closing prices adjusted for dividends and splits, over five years of history. Pair Scanner publishes computed results, Z-scores, probabilities and reversion statistics, and does not display raw prices. For stock pairs, context is drawn in addition from official documents filed with the SEC, which are in the public domain.

The Cross-asset tab contains a fixed selection, including gold and mining companies, cryptocurrencies and related equities, or bonds and banks. Each pair uses available USD histories on shared dates only. When closing times differ, only the closing Z-score is used. Cointegration, divergence and other criteria remain available as for other pairs.

Yes. In the Stocks view, the Same SIC sector filter compares the first two digits of the issuers’ SEC activity codes. Available codes appear in the pair detail. After you select the first symbol, the tester also suggests companies in the same SIC group. Coverage grows in the background; missing codes are shown as missing, never guessed.

The distance method compares normalized price paths and measures squared gaps during a formation period. It offers another way to select pairs; a low distance does not prove that the spread is stationary. Pair Scanner explains the calculation, a numerical example and the differences from cointegration in its guide: https://pairscanner.com/en/distance-method/

Pair trading is a market-neutral strategy that exploits the price spread between two historically linked securities. When the spread moves abnormally far from its mean, the strategy buys the lagging security, sells the other one, and closes the position when the spread normalizes. Developed at Morgan Stanley in the 1980s, it remains a staple of quantitative funds. Pair Scanner automates this approach by evaluating millions of combinations of US securities every night.

Cointegration is a statistical relationship between two price series whose spread remains stable over time, even though each security moves freely. Two stocks can be correlated without being cointegrated: correlation measures simultaneous moves, cointegration tests the stability of the spread. Pair Scanner uses the Engle and Granger test, complemented by a multiple-testing correction and an out-of-sample validation.

The Z-score measures how far the spread between two securities has moved from its mean, expressed in standard deviations. A Z-score of +2 means the spread sits two standard deviations above its average of the last 60 sessions, a zone considered extreme in pair trading. Pair Scanner recomputes it every night and refreshes it during the session from quotes delayed by about fifteen minutes.

The scanner's core is cointegration-based pair trading: a statistical test verifies that the spread between two securities has a demonstrated restoring force. Around that foundation, the tool also serves the other schools: a 20-session divergence measure for the correlation approach (one name takes off, its twin does not follow), a P(A)/P(B) ratio view with its bands for ratio traders, a stock-versus-ETF view to play a name against its sector, and spot currency pairs such as XAU/USD against XAG/USD. All these readings remain market-neutral: you trade the gap between two instruments, never the market's direction.

Every metric shown by Pair Scanner is defined on a public page, accessible without an account or a subscription: cointegration, p-value, q-value, Z-score, signal, out-of-sample validation, reversion rate, half-life, correlation and hedge ratio. The definitions are written for someone discovering pair trading, with no mathematical formalism. See https://pairscanner.com/en/understanding-metrics/

No. Pair Scanner provides statistical information: cointegration tests, Z-scores, reversion histories. No personalized recommendation is issued and the publisher is not a provider supervised by FINMA. Investment decisions remain the sole responsibility of the user; trading involves a risk of loss up to the entire capital involved.