Citi and Apollo will handle loan portfolio with capital from insurance annuity company Athene and Abu Dhabi’s Mubadala Investment Co.

Citigroup and Apollo Global have partnered for a $25 billion private credit and direct lending program, illustrating a growing alliance between banks and non-banks looking for a slice of the lucrative $2 trillion market.

Zelter joined Apollo in 2006 after more than a decade at Citigroup, where he had once served as the chief investment officer of a division that invested in private assets. Before that, he oversaw the bank’s global high-yield and leveraged finance business. Citigroup is a frequent underwriter of debt deals for Apollo’s private equity business.