CORRECTED-BRIEF-BGC Partners says continues to seek negotiated merger with GFI (Sept 15)

(In Sept. 15 brief, corrects last bullet point to say BGC's intention to commence offer to buy GFI, not BGC) Sept 15 (Reuters) - BGC Partners Inc : * Says BGC entities have over the course of several years repeatedly expressed an interest in acquiring GFI Group Inc * Continues to seek negotiated merger with GFI would provide superior value to GFI shareholders, and prepared to begin such negotiations * Reports 13.5 percent stake in GFI Group Inc as of September 3 - SEC filing * On September