LONDON — World stock markets fell Wednesday as investors worried about sovereign credit risks, particularly in Europe, in the wake of Greece's rating downgrade. The FTSE 100 index of leading British shares was down 35.95 points, or 0.7 percent, at 5,187.18 while Germany's DAX fell 62.93 points, or 1.1 percent, at 5,625.65. The CAC-40 was 20.12 points, or 0.5 percent, lower at 3,765.18. Wall Street opened lower despite earlier indications in the futures markets that U.S. stocks were looking to recoup some of the previous session's losses. The Dow Jones industrial average was 39.30 points, or 0.4 percent, lower soon...