What Is Pair Trading and How Does It Work?

Short answer: Pair trading is a strategy where you buy one stock and sell another related stock at the same time, aiming to profit from the gap between the two prices narrowing. The profit comes from the relationship between the two stocks, not from the overall market rising or falling. The rest of this article explains how the trade is built, why it is described as market-neutral, and where it can go wrong.

Last reviewed: 5 November 2026

At a glance

How does a pair trade work step by step?

A pair trade has two parts, called legs. The first is a long position, which means buying shares in one stock. The second is a short position, which means short-selling the other stock: borrowing its shares, selling them, and planning to buy them back later at a lower price.

In a typical setup, the trader buys the stock that has lagged and short-sells the stock that has run ahead within the pair. The trade is profitable if the lagging stock catches up or the leading stock falls back, so that the gap between them narrows. When the gap has closed, the trader closes both legs.

Why is it called market-neutral?

Because the long and short legs offset each other, the trade is described as market-neutral. If the broad market falls, the bought stock may lose value, but the short-sold stock may gain value, so the two effects can cancel out. This is why a broad market fall does not necessarily cause a loss.

The catch is that neutrality covers the market as a whole, not the pair itself. If the stock you bought falls more than the stock you shorted, the trade loses money even on a day when the market is flat. Market-neutral means the trade is designed not to depend on market direction, not that it cannot lose.

How do traders decide when to enter?

A pair trader can track the price ratio of the two stocks each day. This is the price of one stock divided by the price of the other. A ratio that stays fairly steady over time gives a reference point, and the trader can compare today’s ratio to its average.

Entries are usually looked for when the ratio moves well away from that average. The logic rests on the convergence assumption: the strategy expects a temporary divergence to return to its historical average relationship. The word “well” matters here, because the trader has to decide how far from the average is far enough, and that judgement can be wrong.

How are the two sides sized?

Position sizing aims to make the rupee value of the two legs roughly equal, so the hedge is balanced. Equal share counts are not the goal, because two stocks can have very different prices. The goal is equal money on each side.

Here is a hypothetical example with invented figures, not real prices. Suppose Stock X trades at Rs 400 a share and Stock Y trades at Rs 200 a share. A trader who buys 100 shares of X puts in Rs 40,000, so the matching short leg would be 200 shares of Y, which also comes to Rs 40,000.

Which pairs are usually chosen?

Good candidate pairs are typically companies with similar business models, similar sector exposure, and similar sensitivity to macro factors, which are broad economy-wide forces such as interest rates. The logic is that a shared event affects both companies in the same way, so their prices tend to move together.

HDFC Bank and ICICI Bank are often cited as an example of this kind of pair, since both are large private sector Indian banks. A regulatory change affecting banks, for instance, may affect both. The same similarity is also the weakness: if a problem is specific to one bank, the pair can diverge further instead of converging.

What are the risks and catches?

The biggest risk is that the convergence assumption fails. A divergence may not return to its historical average, and the gap may widen instead. In that case the long leg can lose value while the short leg gains, or both can move against the trader, depending on the trade.

A second risk is imperfect hedging. If the two legs are not balanced in rupee terms, or if the two stocks stop behaving as they used to, the offset is weaker than the strategy assumes. Short-selling also adds its own exposure: if the shorted stock rises sharply, the loss on that leg grows for as long as the position stays open.

Frequently asked questions

Is pair trading the same as betting on the market?

No. The strategy is built so that the two legs offset each other, which is why it is described as market-neutral. The result depends on the gap between the two stocks, not on whether the overall market goes up or down.

Can a pair trade lose money even if the market falls?

Yes. A broad market fall does not necessarily cause a loss, but the trade can still lose if the stock bought falls more than the stock shorted. It can also lose if the gap between the two stocks widens instead of narrowing.

Why do traders need the two sides to have equal rupee value?

Equal rupee value helps keep the hedge balanced, so that the two legs offset each other as intended. If one side is much larger, the trade carries more exposure to that one stock than the strategy intends.

What makes two stocks a good pair?

Good candidates are typically companies with similar business models, similar sector exposure, and similar sensitivity to macro factors. Because a shared event affects both in the same way, their prices are more likely to move together.

Sources and last check

Facts in this article were checked against the sources below on 5 November 2026. Rules and figures can change; check the primary source before acting.

• groww.in (broker education)
• dhan.co (broker education)
• upstox.com (broker education)
• zerodha.com (broker education)

This article is general information, not investment advice. MyFinanceBandhu is not a SEBI-registered investment adviser.