In a large bowl, cream sugar and butter. Next add the yogurt and bananas. Combine flour, baking powder and baking soda; add to creamed mixture. Spoon into a greased 9-in. x 5-in. x 3-in. loaf pan. Bake at 350 degrees F for 40-45 minutes or until bread tests done with a toothpick. Cool in pan for 10 minutes before removing to a wire rack.