Concern is again growing that the oil market could turn into a negative for stocks and high-yield bonds, despite Friday’s record closes in the S&P 500 and Nasdaq NDAQ -0.35 % Composite indexes. U.S. crude for September delivery dropped below $40 a barrel on Tuesday, marking its lowest close since April and the 10th decline in 12 trading sessions, before rebounding to end the week at $41.80. Oil is down 18% since early June. Though the decline has been driven largely by a surplus of crude, some money managers fear tumbling oil prices will erode investor sentiment and spread to other markets from U.S. stocks to riskier bonds. Many investors blame oil declines in part for the broad rout early this year that sent the Dow Jones Industrial Average down more than 10%. The correlation between U.S. oil prices and the S&P 500 stock index climbed to a multiyear […]