Instinet Corp. has subleased 140,000 square feet of office space from Charles Schwab Corp. at Plaza 10 in Jersey City's Harborside Financial Center. Instinet will occupy 5 floors for a 15-year lease term. Richard Donohue and Lawrence Tannenbaum of Cushman & Wakefield Inc. in New York are marketing the sublet space for Charles Schwab, while Gary Greenspan and Joseph Cabrera of Cushman & Wakefield in NYC and Ted Koltis of Tishman Real Estate Services worked the deal on behalf of Instinet. Charles Schwab originally leased the entire 594,265-square-foot building from owner/developer Mack-Cali Realty Corp., but the stockbrokers ended up putting the whole property back on the market for sublease. Plaza 10 is still under construction, with completion scheduled for this June.