Why Does Basis Tend to Converge to Zero at the Expiration of a Traditional Futures Contract?

At the expiration of a traditional futures contract, the contract's price must converge to the spot price of the underlying asset. This convergence happens because, at the moment of settlement, the contract's value is defined by the spot price for the final cash settlement or physical delivery.

Any significant difference between the two prices would create an immediate, risk-free arbitrage opportunity that traders would quickly exploit, forcing the prices together.