Countrywide Financial Corp. said Thursday it has agreed to buy almost all of the assets of KB Home’s mortgage business, KB Home Mortgage Co. Terms of the deal were not disclosed.

Calabasas-based mortgage lender Countrywide and the L.A.-based homebuilder also said they formed a 50-50 joint venture that will make residential loans to KB Home customers. The joint venture will sell the same range of products as Countrywide, which will have day-to-day oversight over the business.

“We believe the transition to working directly with an established lending leader makes sense for the benefit of customers and business,” said KB Home Chairman and CEO Bruce Karatz in a statement released by the two companies.

The KB Home unit is a small part of the company’s business. In KB Home’s latest earnings release, for the second quarter, mortgage banking revenue accounted for $10 million of the company’s total $2.1 billion in revenue.

Shares of Countrywide were up 1 percent to $38.81 and KB Home rose 2.1 percent to $76.68 in mid-morning trading Thursday.