Arbitrage

Arbitrage is the practice of exploiting price differences for the same asset across different markets or forms to generate a risk-free (or near risk-free) profit. The classic example: if gold trades at $1,900/oz in New York and $1,905/oz in London, an arbitrageur can simultaneously buy in New York and sell in London, pocketing a $5/oz profit before transaction costs.

Types of Arbitrage:

• Pure/Classic arbitrage: Exploit identical price discrepancies across markets (rare in modern electronic markets)
• Statistical arbitrage (stat arb): Use quantitative models to identify historically correlated assets that have temporarily diverged
• Merger arbitrage (risk arb): Buy the target company's stock after a merger announcement, betting the deal closes at the offer price
• Convertible arbitrage: Buy convertible bonds and short the underlying stock to profit from mispricing
• Crypto arbitrage: Buy on one exchange where the price is lower, sell on another where it's higher
• ETF arbitrage: Exploit price discrepancies between an ETF and its underlying holdings

Why Arbitrage Matters: Arbitrage is the mechanism that makes markets efficient. When arbitrageurs exploit price discrepancies, they buy the underpriced asset (pushing its price up) and sell the overpriced asset (pushing its price down), eliminating the gap. In theory, pure arbitrage should be instantaneous and self-eliminating.

Risks (it's rarely truly risk-free):

• Execution risk: prices change before both legs complete
• Liquidity risk: can't exit the trade when needed
• Funding risk: margin calls before convergence
• Model risk (stat arb): the historical relationship may break down permanently

Hedge funds and high-frequency trading firms dedicate enormous resources to finding and exploiting arbitrage opportunities, which is why they've become increasingly scarce and short-lived.