Ford Motor Co. on Tuesday reported that it swung to a net loss in the fourth quarter due to a large accounting charge on pension plans and the effects of a six-week strike at multiple factories by the United Auto Workers union. The Dearborn, Michigan, automaker posted a $523 million net loss from October through December versus a $1.26 billion profit for the same period a year ago. Ford reported a $1.7 billion noncash accounting loss during the quarter on remeasurement of pension and other post-retirement employee benefits.