Fifth Third Bancorp ( FITB) signed a definitive agreement to sell a 51% stake in its processing business to private-equity firm Advent International through the establishment of a new joint venture.

Fifth Third will retain the remaining 49% percent interest in the new company, Fifth Third Processing Solutions LLC, which is valued at $2.35 billion, the Cincinnati bank said in a statement Monday.

Advent will pay Fifth Third $561 million in cash for its stake in the business and for certain put rights. Fifth Third will capitalize the new company with loans of $1.25 billion and will receive warrants in the new company.

Fifth Third said the transaction is expected to contribute "significantly" to its retained earnings, capital levels and capital ratios, and generate an expected pretax book gain of an estimated $1.7 billion. The deal also will increase the bank's tangible common equity and Tier 1 capital by an estimated $1.2 billion.

Fifth Third joins other financial firms in selling assets to bolster capital, in part because private buyers have been wary of investing directly in banks, the Wall Street Journal reports.

The move by the bank deal shores up the bank's capital base following a $3.45 billion injection from the government. Only nine U.S. banks have received more federal money than Fifth Third, the nation's 14th-largest bank by assets, according to the Journal.