On the heels of the firm's 500th transaction, Boston alternative asset manager Audax Group has closed a fifth private equity fund with $2.25 billion in capital commitments.

The fund, Audax Private Equity Fund V, oversubscribed the $1.75 billion fundraising target. Public and corporate pension funds, insurance companies, endowments, foundations, high net worth families and the firm's senior professionals invested in the fund.

Audax will continue to buy and build lower middle-market companies. Since it was founded in 1999, Audax has raised $12 billion in capital and manages more than $9 billion through the private equity and private debt businesses.

The firm's recent deals include a deal for Justrite Manufacturing, which makes storage products for flammable material, from Baird Capital. Audax also recently bought Dermatology of Northern Colorado, which was added to Audax portfolio company Advanced Dermatology & Cosmetic Surgery. Dermatology of Northern Colorado was Audax Private Equity's 500th transaction.

AllOver Media, which Audax picked up in March, is another company the firm is actively building. In July, the advertising space business acquired Zoom Media's social indoor and family network divisions, adding static posters and digital screens in more than 1,600 venues. Before that, AllOver picked up Ripple Resort Media Inc., an advertising group focused on winter resorts.

For more on Audax, watch our video interview with managing director Jay Jester.