AMEREN CORP. $43 (www.ameren.com) has raised its quarterly dividend by 2.5%, to $0.41 a share from $0.40. The new annual rate of $1.64 yields 3.8%. Ameren should benefit from recent rate increases at its gas-distribution operations. However, most of its power plants burn coal, so it will have to convert them to gas and other fuels to comply with tougher environmental regulations. Hold.