(Adds rankings for Citigroup, Wells Fargo, NYC authority)
Oct 3 (Reuters) - Debt issuance by states, cities, schools and other issuers in the U.S. municipal bond market totaled $323.4 billion in the first three quarters of 2016, a 7.4 percent increase from the same period in 2015, according to Thomson Reuters data on Monday.
Bank of America Merrill Lynch was the top underwriter of muni bonds during 2016's first nine months with 408 deals, totaling nearly $50 billion.
Citigroup came in second with 428 deals totaling $37.6 billion. Wells Fargo & Co, which stands to lose underwriting business due to a sales scandal, ranked fifth with 244 deals totaling $20.85 billion.
So far, California's treasurer and Illinois' governor have suspended the bank from underwriting their states' bonds, while the city of Chicago could take up a two-year ban as soon as this week.
Wells Fargo staff opened checking, savings and credit card accounts without customer approval for years to satisfy managers' demand for new business, according to a $190 million settlement with regulators reached on Sept. 8.
California was the biggest debt issuer in the first nine months of 2016 with 10 deals totaling $7.27 billion, according to Thomson Reuters data. New York City's Transitional Finance Authority ranked second, with 14 deals totaling $4.75 billion. (Reporting By Karen Pierog; Editing by Chris Reese, Bernard Orr)