No-Arbitrage Principle

The No-Arbitrage Principle is the foundational assumption in financial theory that suggests in an efficient market, it is impossible to earn a risk-free profit by exploiting price differences. If an arbitrage opportunity exists, market participants will quickly act to buy the cheaper asset and sell the more expensive one, driving prices back into equilibrium.

This principle underpins almost all derivative pricing models, as they rely on the assumption that no riskless profit can be made without investment. In the context of cryptocurrency, while markets are sometimes less efficient than traditional finance, the no-arbitrage principle remains the target state for protocols and market makers.

When price discrepancies occur between exchanges, arbitrageurs act as the market mechanism that restores alignment. This principle forces consistency across different financial instruments, such as spot and futures, ensuring that the market remains orderly.

It provides the logical framework for traders to understand why certain strategies, like conversions and reversals, are viable and why they eventually cease to be profitable as the market corrects.