Durable goods orders increased by a surprisingly strong 4.6% in December, closing out the year with the highest monthly gain since September. The increase was nearly three times above the consensus forecast of 1.6%, based on Econoday’s estimates. Much of the gain was due to a sharp rise in aircraft orders, a volatile component that often trips up many short-term predictions for this series. Excluding transportation, new orders for durable goods still advanced, but by a considerably lesser 1.3% pace. Business investment (capital goods orders less defense and aircraft), by contrast, increased a tepid 0.2%, which suggests that corporate America’s appetite for laying out large sums of money for plant and equipment remains sluggish.