What Arbitrage Strategy Forces the Futures Price and Spot Price to Converge?

The cash-and-carry and reverse cash-and-carry arbitrage strategies are the primary forces driving convergence. When the futures price deviates too far from the spot price plus cost of carry, arbitrageurs step in.

They buy the undervalued asset and sell the overvalued one. This simultaneous buying and selling pressure on both the spot and futures markets pushes the prices back into alignment, thus forcing convergence.