N.Y. Gen. Bus. Law § 339-C
A broker, who, being employed by a customer to buy and carry upon margin the stocks, bonds or other evidences of debt of a corporation, company or association, while acting as broker for such customer in respect of such stocks, bonds or other evidences of debt, sells for his own account the same kind or issue of stocks, bonds or other evidences of debt of such corporation, company or association, with intent to trade against the customer's order, or, who, being employed by a customer to sell the stocks, bonds or other evidences of debt of a corporation, company or association, while acting as broker for such customer in respect to the sale of such stocks, bonds or other evidences of debt, purchases for his own account the same kind or issue of stock, bonds or other evidences of debt of such corporation, company or association, with intent to trade against the customer's order, is guilty of a misdemeanor.
N.Y. Gen. Bus. Law § 339-C