LPL Investment Holdings Inc., one of the financial service industry’s most successful privately-held  broker-dealers, is finally going public.

LPL, parent company of LPL Financial Corporation, announced today it had filed a registration statement on Form S-1 with the Securities and Exchange Commission in connection with the initial public offering of its common stock.

The largest independent contractor broker-dealer in the US, LPL had 12,026 advisors as of 31 March, a more than 300 per cent increase over ten years. The  firm’s initial public offering is valued at $600 million, according to the SEC filing.

LPL’s IPO move has been anticipated for years. In 2005, the firm sold a 60 per cent stake to two private-equity firms, Hellman & Friedman LLC of San Francisco and Texas Pacific Group of Fort Worth.

Goldman Sachs and Morgan Stanley will be the senior underwriters for the proposed offering, with Bank of America / Merrill Lynch and JP Morgan serving as junior underwriters.