Due to a contract squabble, Warren Langley has resigned as chief executive officer of Nasdaq Liffe Markets (NqLX), the new single-stock futures exchange created by a joint venture between Nasdaq and Liffe. Langley, who was named CEO of NqLX on June 25, has been replaced-at least on an interim basis-by Bob Fitzsimmons. Fitzsimmons, a former NASD executive, was recently named president and COO of NqLX, and is now also serving as acting CEO. NqLX, scheduled for launch later this year, has also named David Harris its general counsel. Harris, who previously served the same role for both the NASD and the Nasdaq Stock Market, will be responsible for providing legal counsel and advice to the senior management of NqLX. Headquartered in New York, the all-electronic, U.S.-based market plans to trade single-stock futures contracts via Liffe's Liffe Connect electronic trading engine.