Stocks fell Friday, capping the biggest weekly decline of the year for the S&P, after the Labor Department said the nation added fewer jobs than economists forecast in March. American Express and Coca-Cola paced losses among the largest companies. F5 Networks led declines among tech shares, after it reported preliminary results below its forecast. Payrolls grew by 88,000 workers last month, the smallest in nine months. The survey, a closely watched economic indicator, dented investors’ confidence that the nation was poised for a sustained recovery. Looking ahead, Alcoa unofficially kicks off the first-quarter earnings season on Monday.