WASHINGTON (AP) — The U.S. supply of computer chips has fallen to alarmingly low levels, raising the prospect of factory shutdowns. That’s according to the Commerce Department, which on Tuesday said companies that use semiconductors are down to less than five days of inventory. The department cited its survey of 150 companies that found chip inventories had dropped sharply from 40 days in 2019. The chips used in the production of automobiles and medical devices are especially scarce. The department said demand for chips was up 17% last year from 2019.