A promise to continue returning billions of dollars to shareholders couldn't make up for a lackluster first quarter from Schlumberger (SLB -1.23%) on Friday. After the company unveiled those results, investors generally traded out of the stock and left it with a nearly 2% loss on the day. Meanwhile, the S&P 500 index landed in positive territory with a 0.6% increase.Drops in headline fundamentalsBoth revenue and profitability declined for Schlumberger on a year-over-year basis during the quarter. The former ...