Stocks plummeted in midday trading Tuesday with the Dow Jones Industrial Average down more than 300 points after several blue-chip companies reported weak earnings. Among the worst performers, Microsoft plummeted nearly 10%. The tech giant reported a drop in quarterly profit, a result of restructuring efforts and last year's $7 billion acquisition of Nokia's mobile phone business. Caterpillar plummeted more than 7% as lower oil prices hurt the company's bottom line. Net profit tumbled nearly 25%, while revenue slid 1.1%. Durable goods orders missed expectations by an enormous margins with headline orders down 3.4%.