Arbitrage - Risks

Risks

Arbitrage transactions in modern securities markets involve fairly low day-to-day risks, but can face extremely high risk in rare situations, particularly financial crises, and can lead to bankruptcy. Formally, arbitrage transactions have negative skew – prices can get a small amount closer (but often no closer than 0), while they can get very far apart. The day-to-day risks are generally small because the transactions involve small differences in price, so an execution failure will generally cause a small loss (unless the trade is very big or the price moves rapidly). The rare case risks are extremely high because these small price differences are converted to large profits via leverage (borrowed money), and in the rare event of a large price move, this may yield a large loss.

The main day-to-day risk is that part of the transaction fails – execution risk. The main rare risks are counterparty risk and liquidity risk – that a counterparty to a large transaction or many transactions fails to pay, or that one is required to post margin and does not have the money to do so.

In the academic literature, the idea that seemingly very low risk arbitrage trades might not be fully exploited because of these risk factors and other considerations is often referred to as limits to arbitrage.