The fundraising underscores the popularity of so-called co-investments, which allow investors to buy stakes in specific companies at the invitation of private equity firms on more favorable fee terms than their general buyout funds. They also allow the private equity firms to pursue bigger acquisitions.

The new fund, AlpInvest Co-Investment Fund VIII, exceeded its initial target of $3 billion. Just like its predecessors, the fund will invest alongside private equity firms in businesses in consumer, industrials, healthcare, technology, financial and business services, mostly in North America, Europe, and Asia, Richard Dunne, co-head of co-investments at AlpInvest, said in an interview.

"We are seeking to find high-quality investment opportunities where we are partnered with a lead general partner we know really well to execute the investment thesis of that deal," Dunne said.

AlpInvest has raised more than $12 billion for its co-investment funds, which have made about 280 acquisitions since the firm was founded in 2000. It has $55 billion in assets under management.

(Reporting by Chibuike Oguh in New York; Editing by Cynthia Osterman)

By Chibuike Oguh