Canada Pension Plan Investment Board (CPPIB) said on Tuesday it has agreed to buy GE Capital's private equity lending portfolio for $12 billion, in a deal that will vastly expand the largest Canadian pension fund's lending business.

GE's Chicago-based Antares unit is the leading lender to middle market private equity-backed transactions in the US. Over the past five years, Antares has provided more than $120 billion in financing.

"This acquisition exemplifies our strategy to achieve scale in key sectors through platform investments," said CPPIB's Chief Executive Officer Mark Wiseman in a statement. "It secures a market-leading business that is exceptionally well positioned."