California State Treasurer John Chiang on Wednesday announced a sweeping suspension of business relationships with Wells Fargo & Co. as punishment for the company's defrauding of customers.

In addition, Chiang vowed to work with the state's two giant public pension funds to change the management structure at the bank, which is California's oldest financial institution.

The sanctions, which will last for 12 months, include suspending Wells Fargo as a managing underwriter on state negotiated bond sales, Chiang said. California is the nation's largest issuer of municipal debt.