The list of Wall Street investors in the International Securities Exchange ( ISE) just got a little longer.

The New York-based options exchange said Monday that E*Trade Financial ( ET), Nomura Securities and Van de Moolen ( VDM) each have taken an equity stake in the company's newly planned stock exchange. ISE did not disclose how big a stake each of the financial firms will have in the new exchange.

Earlier this year, the ISE announced plans to launch a new stock exchange called ICE Stock Exchange. At that time, ISE said Bear Stearns ( BSC), JP Morgan Chase ( JPM), Knight Capital ( NITE) and Deutsche Bank ( DB) were all joining as equity investors in the new venture.

ISE went public a little over a year ago. The company's new electronic stock exchange is expected to open for business later this year.

In early trading, shares of ISE were down 2 cents to $38.44.