Josef Neckermann, 79, one of Germany's best-known businessmen and a former Olympic champion horseman, died Sunday of lung cancer at his home in Goetzenhain near Frankfurt, Germany. He headed the German Sport Aid organization for more than two decades. Born in Wurzburg, he wanted to join the German cavalry but went into business because of the early death of his father. In 1935, he took over and managed Jewish retail businesses that had been confiscated by the Nazis. He worked for the Third Reich during World War II. In 1948, he opened a wholesale textile operation in Frankfurt that grew into one of Germany's largest mail-order businesses, which still bears his name.