Copper futures fell Thursday, capping the first monthly drop since October, after the U.S. economy expanded less than forecast last quarter and the International Monetary Fund signaled a lower growth forecast for the country.

U.S. gross domestic product increased at a 0.1 percent annual rate, below the 0.5 percent median forecast of 83 economists surveyed by Bloomberg, government data showed today. About $85 billion in spending cuts due to begin tomorrow will shave at least 0.5 percentage point from expansion, currently estimated at 2 percent this year, an IMF spokesman said.

“The slow GDP growth we’re seeing is a concern going forward, and the IMF adds to those fears,” David Meger, the director of metal trading at Vision Financial Markets in Chicago, said in a telephone interview. “The firmness in the dollar is also pressuring commodities across the board.”

Copper futures for May delivery declined 0.5 percent to settle $3.5475 a pound at 1:19 p.m. on the Comex in New York. This month, the price dropped 4.9 percent.

Stockpiles tracked by the London Metal Exchange increased for the fifth straight month, while inventories monitored by the Shanghai Futures Exchange are up 49 percent since the end of June.

On the LME, copper for delivery in three months declined 0.7 percent to $7,815 a metric ton ($3.54 a pound).

Aluminum fell 0.7 percent to $2,005 a ton, the lowest settlement in three months. The price dropped for the ninth straight session, the longest slump since late June.

Nickel, tin, lead and zinc also slid.