Jumbo Mortgage Originators in 2000 Washington Mutual, benefiting from last year’s strong adjustable-rate lending environment and robust home sale market, easily topped the list of the largest ARM originators in 2000, according to a year-end ranking by Inside Mortgage Finance. The West Coast-based thrift giant also took top honors among jumbo mortgage originators in the country, thanks in large measure to its dominance of the California mortgage market,