NEW YORK (Reuters) -CoinEx was sued on Wednesday by New York Attorney General Letitia James, who accused the cryptocurrency exchange of transacting business illegally because it did not register with the state. In papers filed with a New York state court in Manhattan, James accused CoinEx of having "engaged in repeated and persistent fraudulent practices." She said CoinEx's failure to register as a commodity broker-dealer, securities broker or securities dealer before buying and selling tokens violated the Martin Act, a powerful state law used to fight financial fraud.