Carlyle Group Inc. arranged a first-of-its-kind financing that will commit more than $5 billion to seed its next flagship buyout fund while repaying investors in some of its older vintages, according to people with knowledge of the matter.

The structured credit deal will total $8.5 billion, roughly half of it composed of bank debt, with the rest in preferred equity and common equity, the people said, asking not to be identified discussing confidential details.