Coffee prices swung sharply over the past week as the prospect of US tariffs on Brazilian imports and a sudden drop in shipments from the world’s top grower rattled global supplies. Arabica futures initially slid 2.1% on 6 August but reversed course a day later, climbing as much as 2% in New York, while robusta contracts in London advanced 2.9%. Brazil’s green-coffee exports fell 20% in July from a year earlier, according to the country’s trade ministry. Growers have been withholding beans in anticipation of higher prices, deepening a supply squeeze that has pushed exchange-monitored inventories to their lowest level in more than a year. The threatened US levies, aimed at a wide range of Brazilian products including coffee, have added to the uncertainty for roasters and traders. The volatility in coffee markets coincided with a broad rally in soft commodities. Cocoa futures recorded their largest one-day gain since December on 11 August after forecasters trimmed expectations for the upcoming West African crop, fuelling concerns over tight chocolate-making supplies.