A key measure of Chinese copper demand just sank to zero, another sign that global prices are not balanced with what buyers in the biggest market are prepared to pay.

Premiums paid on imported refined copper extended a months-long decline to reach zero for the first time in Shanghai Metals Market data going back to 2017. The unusually low levels come just days after copper on the London Metal Exchange rallied to a two-year high near $10 000 a ton.

Copper is up nearly 15% this year on the LME on bets that a global recovery in manufacturing — and growth in demand from new-energy applications — will spur long-term gains. But in China, inventories are rising, spot prices are trading at a discount to futures, and smelters are turning to exports.

Customers of one of China’s biggest copper traders have been reluctant to buy the metal since March because of weak downstream demand. Fabricators — firms that buy copper and make products like wires or tubes — needed lower prices, Wang Wei, general manager at Shanghai Wooray Metals Group , said in an interview Tuesday.

The indicator that’s just fallen to zero is known as the “Yangshan” premium, named after an area of Shanghai that’s dominated by warehouses storing imported copper. Regional premiums are paid on top of global exchange prices, so offer an insight into buying appetite. Their peak since 2017 was just above $250 a ton.

Copper rebounded on Wednesday from its biggest daily decline since early February after US data rekindled hopes for the Federal Reserve to cut interest rates.

Metals have swung during a busy week for US data releases that are being closely watched because they might affect the Fed’s monetary policy path. Business activity in the world’s largest economy expanded in April at the slowest pace this year, according to a gauge on Tuesday.

Any signs of a cooling US economy are a potential boon for metals by implying that the Fed can go ahead with easing this year. Still, stubborn inflationary pressures also underscore strong demand for commodities.

Copper gained 1.2% to $9,819 a ton at 1:35 p.m. Shanghai time, after closing down 1.3% on Tuesday. Most other metals also rose, with zinc up 1.1% and tin rallying 1.9% after a 7.4% slump in the previous session.