Private equity firm Marlin Equity Partners has closed a $400 million fund that will target lower middle market investments.

The fund, called Marlin Heritage LP, was offered to investors in Marlin's fourth flagship fund, and closed in less than three months. Marlin Heritage will focus on lower middle market businesses in the technology, business services, health care, consumer and manufacturing sectors.

Los Angeles-based Marlin has closed five private equity funds since it was started in 2005, and has more than $3 billion in capital under management. In October, the firm announced a deal to take Tellabs (Nasdaq: TLAB) private for $891 million. 

Bruce Ettelson and Karin Orsic of Kirkland & Ellis LLP served as Marlin's legal counsel for the fund formation, which was announced April 1. 

Private equity firms have increasingly been looking to get involved in the lower end of the middle market. For more on the lower middle market, see "How Brynwood Partners Pleased WalMart with Zest Repackage" and "Life in the Lower Middle Market."