Some exchanges moved to rein in risk, with the margins for certain Comex silver futures contracts raised from Monday. When an exchange boosts margin requirements, traders have to put up more cash to keep their positions open. Some speculators don’t have the extra money, so they’re forced to shrink or close their trades.

Despite the pullback, gold and silver remain on track for their best annual performances since 1979. The metals have been supported by high central-bank purchases, inflows to exchange-traded funds and three successive rate cuts by the US Federal Reserve. Lower borrowing costs are a tailwind for commodities, which don’t pay interest.