QUEBEC CITY, Canada, June 12 -- EXFO Electro-Optical Engineering Inc. has filed a registration statement with the US Securities and Exchange Commission. EXFO has also filed a preliminary prospectus with the securities commissions in the Canadian provinces concerning a proposed initial public offering of 6 million of its subordinate voting shares. An underwriting group lead by Merrill Lynch & Co. and co-managed by RBC Dominion Securities, Wit SoundView and CIBC World Markets will make the public offering. The registration statement states that all 6 million subordinate voting shares will be offered by EXFO. The underwriters also have an option to purchase 900,000 additional subordinate voting shares in case of any over-allotments. EXFO will use a portion of the proceeds to repay outstanding promissory notes and debt.