What does arb mean?
Arb is the abbreviated, informal form of arbitrage, the simultaneous buying and selling of an asset in different markets to capture a profit from small price differences. The term belongs chiefly to the vocabulary of traders, fund managers, and financial journalists, appearing on dealing desks and in market commentary far more often than in everyday speech. Used loosely, an arb can denote either the exploitable price gap itself or the trader who exploits it. Because genuine arbitrage opportunities are typically fleeting and thin-margin, the word carries connotations of speed, technical sophistication, and near-riskless gain, and phrases like stat arb (statistical arbitrage) have grown out of it. For readers of financial news, recognizing arb is useful shorthand for understanding how modern markets are arbitraged toward efficiency.
nounAn informal abbreviation for arbitrage, the practice of profiting from price differences of an asset across different markets; it is also used to mean a person who engages in such trading.
- A price discrepancy that can be exploited for riskless profit through arbitrage.
- A trader who specializes in arbitrage transactions.
"The desk made a tidy profit on the arb between the London and New York prices."
"Traders spotted an arb when gold traded cheaper in Zurich than in New York."
"She spent her early career as an arb on a fixed-income desk."
When counting individual arbitrage opportunities or traders, the plural arbs is standard; the practice itself is usually treated as uncountable.
"There were several arbs open between the two exchanges that morning."
Wall Street's quickest profits have a nickname just three letters long: the arb.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of arb
Arb arose as a natural spoken clipping of arbitrage, a term borrowed into English from French in the nineteenth century that itself derives from the Latin arbitrarī, meaning to judge or assess. The same Latin root gives English words such as arbiter, arbitration, and arbitrary, all concerned with judgment or discretion. As arbitrage became central to modern trading, the clipped form spread through British and American financial circles as convenient jargon.
How arb is actually used
Arb is informal or professional jargon, common in trading floors and financial journalism rather than formal writing. It functions both as an uncountable mass noun for the practice and, less often, as a countable noun for an individual opportunity or person.
Easily confused with arb
Arbor refers to a leafy garden shelter or, in anatomy and botany, a tree-like structure, whereas arb is financial shorthand for arbitrage.