Shares of the Los Angeles-based company opened at $41, after pricing Wednesday at the low end of the expected range; the company sold less shares than anticipated.

Oaktree, which had $75 billion of assets under management as of the end of 2011, priced 8.84 million shares at $43, raising $380.3 million. It had intended to sell 11.3 million shares at between $43 and $46 each.

The offering valued Oaktree at around $6.5 billion.

Oaktree's IPO is viewed by some investors as a litmus test for a public offering from Carlyle Group, which is expected to kick off its IPO roadshow next week.

Private equity firms haven't fared well in the public markets. Blackstone Group LP (BX.N), the world's largest private equity firm, has lost around half its market value since its IPO in 2007, before the financial crisis took hold in the U.S.

Oaktree first sold about 13 percent of itself to clients in 2004 and then sold 16 percent of itself for net proceeds of $944.2 million to outside institutional investors in 2007 in a private placement.

Oaktree founders Howard Marks and Bruce Karsh founded Oaktree Capital Management in 1995 with four other partners, all coming from asset manager TCW Group Inc.

Marks and Karsh each had a net worth of $1.5 billion as of March 2012, according to Forbes.

(Reporting By Olivia Oran; Editing by Gerald E. McCormick)