Alan B. Slifka, a New York investment manager who used his fortune to promote harmony among Israeli Arabs and Jews and to give the Big Apple Circus its start, died on Friday at his home in Los Angeles. He was 81 and also had a home in Manhattan. The cause was cancer, his wife, Riva Ritvo-Slifka, said. Mr. Slifka already had more than 30 years’ experience in the financial industry in 1981 when, with initial assets of $50 million, he started an investment management company bearing his name. Known today as Halcyon Asset Management, the company manages more than $10 billion. With $500,000, Mr. Slifka started the Abraham Fund Initiatives, named for the biblical patriarch of both Arabs and Jews. Since its establishment, the fund has provided more than $10 million in grants for a range of educational programs to dispel stereotypes and to foster Jewish-Arab cooperation in health, social services and women’s rights. An urge to give something to his hometown, New York, spurred Mr. Slifka to become the founding chairman of the Big Apple Circus in 1977. After graduating from Yale in 1951, Mr. Slifka earned a master’s in business administration at Harvard in 1953. He then joined the financial firm L. F. Rothschild & Company, where he worked as a securities analyst for 32 years, rising to partner before leaving to start his own company. Born in Manhattan on Oct. 13, 1929, Alan Bruce Slifka was the twin son of Joseph and Sylvia Slifka. His father owned textile and real estate businesses. Besides his wife and his twin sister, Barbara Slifka, he is survived by three sons, Michael, Randolph and David; two stepdaughters, Torrie and Skye Ritvo; a stepson, Max Ritvo; and three grandchildren.