Countrywide Financial Corp. on Tuesday urged shareholders to vote for its acquisition by Bank of America Corp.

The struggling Calabasas-based lender said in a filing with Securities and Exchange Commission that the merged companies would benefit shareholders because it would form the “largest mortgage operation in American history.”

Countrywide also said shareholders would benefit from the “upside potential” of the combination, while adding stability to its business.

Shareholders are scheduled to vote on the $4 billion transaction at a June 25 meeting. A majority of the shareholders must vote their approval for the merger to be consummated.

Shares in Countrywide closed up 3.4 percent to $5.50 Tuesday.