U.S. stocks were mixed on Thursday, with the Dow Jones Industrial Average retreating from the closely watched 20,000 level. The ADP Employment Report showed private payrolls rose by 153,000 in December, missing estimates of 170,000. The report typically foreshadows Friday's official jobs numbers from the government. Shares of Walgreens Boots Alliance were in focus after reporting adjusted first quarter earnings of $1.10 a share, beating estimates by a penny. Revenue dropped 1.8% year over year to $28.5 billion, missing forecasts of $29.2 billion. Walgreens is in the process of acquiring Rite Aid RAD for $9.5 billion. Shares declined 0.5% on Thursday. Constellation Brands shares rose after reporting adjusted third quarter earnings of $1.96 a share, topping estimates of $1.72. Revenue rose 10% year over year to $1.8 billion, matching estimates. Beer sales rose 16%, topping the 5% increase in wine sales. The stock is up 2.3% over the past 12 months. TheStreet's Scott Gamm reports from Wall Street.