The role of algorithmic traders as arbitrageurs and their impact on price efficiency in the foreign exchange market are examined. Algorithmic traders do not improve price efficiency by detecting and exploiting mispriced currency pairs. On the contrary, algorithmic traders contribute to the creation of possible arbitrage opportunities as a byproduct of intensified competition among liquidity providers. On the other hand, the same market-making competition also prevents the creation of arbitrage opportunities via tightening of spread. Moreover, the leftover inventory problem impedes the implementation of round-trip arbitrage trades — thereby rendering many “arbitrage opportunities” that do appear spurious. The latter two factors explain the reduced occurrence of arbitrage opportunities under the increased algorithmic trading presence observed in data.