Stocks finished lower Monday as the major indexes gave up early gains quickly. Volume was higher on both exchanges, according to preliminary data. The Nasdaq fell 0.8%; the S&P 500 dropped 0.7%; and the Dow Jones industrial average gave up 0.6% in the stock market today. Dow component McDonald’s (MCD) fell nearly 4% in heavy volume. Investors were spooked by disappointing same-store sales.