Today's arbitrage profit was $966! The logic behind arbitrage is this: when the price difference between spot and futures gold is unreasonable, you simultaneously perform the opposite operation to lock in profits, and then automatically profit from the price difference when the time comes. In practice, there will be transaction fees, delivery costs, margin requirements, etc., so it's not completely risk-free, but theoretically it's much more stable than simply trading gold directly. Ordinary retail investors generally don't do this directly; it's mostly done by institutions or professional traders. This truly achieves almost risk-free arbitrage!