A type of arbitrage (inter-market price differential) that involves only one side of the arbitrage transaction. For example, a trader may only buy low in the market without completing a full circle by selling high. In currency market, this means the arbitrage trade starts in one currency and ends in another (two legs), rather than starting and ending in the same currency (four legs).

One way arbitrage is an attempt on capitalize on violations to the law of one price (LOP): either for lending rate (bid) or borrowing rate (ask). In that sense, one-way arbitrage comes in two forms: owner arbitrage (OA) and borrower arbitrage (BA).

It is also known as quasi-arbitrage.