Mr. Rosenwald carried on a commitment to charity established by his father, Julius, a chairman and builder of Sears, Roebuck & Company, and was one of the three signatories to the agreement that founded a nationwide United Jewish Appeal in 1939. A private investor, Mr. Rosenwald had business interests at various times in enterprises that included the American Securities Corporation, an investment bank; Western Union International, and Ametek, a maker of precision instruments and small electric motors, like those used in vacuum cleaners. He was nevertheless best known for his tireless philanthropic dedication. Mr. Rosenwald, one of the five children of Julius Rosenwald and the former Augusta Nusbaum, was born in Chicago in 1903. He earned a bachelor of science degree at the Massachusetts Institute of Technology in 1924, studied liberal arts at Harvard University for a year, then attended the London School of Economics. Mr. Rosenwald was married three times. His first marriage, to Renee Scharf in 1928, ended in divorce in 1935. In 1938, he married Mary Kurtz, who died in 1985, and last year, he married Ruth G. Israels, who survives him. Mr. Rosenwald is also survived by three daughters, Nina Rosenwald, Elizabeth R. Varet and Alice R. Sigelman, all of Manhattan; a stepson, Michael J. Israel of Manhattan; five grandchildren, and two step-grandchildren.