Wichita ? Entergy-Koch LP, a joint venture of subsidiaries of Wichita-based Koch Industries and New Orleans-based Entergy Corp., is selling its energy trading business to Merrill Lynch & Co.

Koch spokeswoman Mary Beth Jarvis said the 180 employees of Entergy-Koch in Houston and 100 employees in London would become employees of Merrill Lynch when the deal closes during the fourth quarter. Terms of the sale agreement announced Thursday were not disclosed.

Koch pioneered weather derivatives in 1997 as a risk management tool for industries facing the risk of losses resulting from adverse weather. Entergy-Koch, formed three years ago as a 50-50 joint venture, has become the industry leader in trading natural gas, electricity and weather-related contracts. The business grew steadily as other companies got out of energy trading in the wake of the collapse of Enron Corp.