Exhibit 2.1 AMENDMENT NO. 1 TO STOCK PURCHASE AGREEMENT THIS AMENDMENT NO. 1, dated as of March 23, 2004, to the STOCK PURCHASE AGREEMENT, dated as of February 2, 2004, is entered into by and among Ameren Corporation, a Missouri corporation...Stock Purchase Agreement • March 24th, 2004 • Cilcorp Inc • Electric & other services combined
