First Chicago will buy its Brazilian affiliate.

The parent company of First National Bank of Chicago said it had won Federal Reserve Board approval to purchase nearly all of the capital stock of the Brazilian investment bank Banco Denasa de Investimento S.A. The company’s wholly owned subsidiary, First Chicago International Finance Corp., will increase its 44.5% stake in Banco Denasa to 98%. First Chicago has taken more than $15 million in write-offs because of poor performance at the Brazilian bank.