NEW YORK (Reuters) -AlpInvest Partners has raised $4.1 billion for its ninth co-investment fund, an executive at the unit of private equity group Carlyle said, showing continued appetite among investors for access to buyout firms' dealmaking.

The size of AlpInvest Co-Investment Fund IX (ACF IX), and related strategies, exceeds the $3.5 billion eighth iteration of the fund raised in 2021.

Richard Dunne, who leads AlpInvest's co-investment team alongside Roberto Torrini, said the firm's success in raising an enlarged fund came from securing strong support from previous investors but also inflows from new investors wanting exposure to private equity buyouts.

"Part of our value proposition is giving investors access to a part of the market that we believe is incredibly difficult for them to replicate," Dunne said in an interview.

Co-investors join with buyout firms to provide the capital needed to fund an acquisition. As co-invest opportunities are restricted to a few parties on each deal, co-investment funds allow numerous financiers to gain access at the same time - opening the door for smaller, or newer, money managers to participate, as well as the largest institutional investors.

AlpInvest began raising ACF IX in 2023, and ultimately drew contributions from 185 global investors, including pension funds, asset managers and family offices. The extended timeframe for the raise helped draw in additional new backers, Dunne said.

"For newer investors to the asset class, we believe we are a compelling option for them, so staying open for longer is always a good idea and that helped drive us to the finish."

ACF IX will invest in whole-company buyout transactions as well as stake purchases, across industry sectors globally.

Dunne said among the best investments for ACF IX are backing middle-market transactions, as private equity firms are making good acquisitions in this part of the market, at prices roughly a 15% to 20% discount to what similar assets would have cost during the peak buyout years at the start of the decade.

AlpInvest has committed upwards of $19 billion across more than 400 equity co-investments over the past 25 years. The money manager's broader platform includes strategies which buy stakes in other private equity funds, and provide financing to the buyout industry.