As the leader of Salomon Brothers in the 1960s and ’70s, Mr. Salomon, who was known as Billy, steered the bank beyond the sleepy market for United States Treasury debt and transformed it into a full-service firm with particular expertise in trading bonds. Among the young traders of that aggressive era were William E. Simon, who went on to be Treasury secretary, and Michael R. Bloomberg, the future mayor of New York. By the 1980s, when Mr. Salomon had retired and the firm was run by John H. Gutfreund, Salomon Brothers had become a fearsome player on Wall Street. But its star fell as it became embroiled in a scandal over Treasury bond auctions in the early 1990s. Mr. Salomon, who skipped college to join the firm at 19, was born in New York on April 2, 1914. He joined Salomon Brothers in 1933, after graduating from high school, so that he could earn enough money to marry his high school sweetheart, Virginia Foster. He became managing partner in 1963 and retired in 1978. In recent years, Mr. Salomon kept an office at Citigroup, which acquired Salomon through a merger with the insurance firm Travelers in 1998. A secretary who worked for him from 2000 to 2011 was convicted last year of stealing $1.3 million by skimming from his checking account. His wife of more than 70 years died in 2008. In addition to his son, Peter, Mr. Salomon is survived by his daughter, Susan Salomon Neiman; four grandchildren, and three great-grandchildren. Mr. Salomon’s father, Percy, started the firm with his two brothers in 1910, breaking from their father’s Orthodox Jewish tradition and making a point of staying open on Saturday mornings. To bolster their credibility, they recruited Morton Hutzler, who came from a Baltimore department store family and had a seat on the New York Stock Exchange.