As U.S. investigators scrutinize how banks and hedge funds trade large blocks of stock, Goldman Sachs Group Inc. is pulling back from at least one money manager whose communications have drawn interest from authorities, according to people with knowledge of the matter. The investment bank is cutting business ties with Joseph Samuels’s Islet Management, the people said, asking not to be identified discussing private dealings. The reason for the decision -- and whether it relates to the investigation -- couldn’t immediately be determined. Neither Goldman nor Islet have been accused of any wrongdoing in the inquiry touching a ...