Arbitrage

Stock trading dictionary: meaning, example and how traders use it.

Last updated: October 17, 2026

Definition: Arbitrage is the practice of buying an asset in one market and simultaneously selling the same or an equivalent asset in another at a higher price, capturing the difference. Pure arbitrage aims to profit with little or no market risk.

How arbitrage works

Markets connect the same asset across many venues. If identical shares trade at slightly different prices on two exchanges, a trader can buy where it is cheap and sell where it is expensive at the same moment. The act of doing so pushes the prices together, which is why arbitrage helps keep markets efficient.

Because such gaps are usually tiny and short-lived, most classic arbitrage today is performed by firms with fast technology and low trading costs. Opportunities that persist usually involve some risk, cost, or constraint.

Arbitrage depends on the law of one price: identical assets should trade at the same price once costs are accounted for. When that relationship breaks, an arbitrageur steps in. In modern markets this activity is largely automated, and the speed at which gaps close is one reason quoted prices for the same stock rarely differ much across trading venues for long.

Example: a simple arbitrage trade

Suppose a company's shares trade at $50.00 on one exchange and the equivalent depositary shares trade at the equivalent of $50.20 elsewhere after currency conversion. A trader buys 10,000 shares at $50.00 and sells 10,000 at $50.20, locking in $0.20 per share, or $2,000 before costs.

If commissions, currency conversion, and fees total $1,500, the net profit is $500. If execution of either leg is delayed and the price moves, the profit can vanish or turn into a loss.

Common types of arbitrage

  • Spatial or cross-market: the same security priced differently across venues.
  • ETF arbitrage: authorized participants create or redeem ETF shares when the fund's price drifts from the value of its holdings.
  • Index or cash-and-carry arbitrage: trading a futures contract against the underlying basket when the futures price strays from its theoretical value.
  • Merger arbitrage: buying a takeover target below the offer price and betting the deal closes, a strategy that carries real deal risk.
  • Options arbitrage: exploiting mispricings between calls, puts, and the underlying stock.
  • Statistical arbitrage: trading historically related securities when their relationship diverges; despite the name, it is not risk-free. A related idea, the carry trade, exploits interest-rate differences but carries currency risk.

Risks and limitations

True risk-free arbitrage is rare. Execution risk, financing costs, short-sale restrictions, and counterparty risk all reduce or eliminate profits. Strategies labeled arbitrage that rely on leverage and historical relationships can suffer large losses when those relationships break down.

Capital and margin requirements also limit how large a position an arbitrageur can hold.

Frequently asked questions

Is arbitrage legal?

Yes. Arbitrage is a legal and common trading activity, and it generally helps align prices across markets.

Is arbitrage risk-free?

Pure arbitrage is designed to be nearly risk-free, but in practice execution delays, costs, and financing create risk. Merger and statistical arbitrage carry significant risk.

Can individual investors do arbitrage?

Simple price gaps are usually captured by high-speed firms within fractions of a second, so they are hard for individuals to exploit. Strategies like merger arbitrage are accessible but involve real risk.

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For information only, not investment advice. See the disclaimer.