Arbitrage Pricing Theory

Arbitrage defines the procedure of continuously buying a security for privacy, currency, or commodity on one market and selling it in another.  Price variations between the two markets give the arbitrageur his or her profit. The arbitrage pricing theory is based upon the concept of arbitrage, and define how assets should be valued if there were no riskless arbitrage opportunities.  When security markets are competitive and effective, then chances to profit from arbitrage should be nonexistent.