Preheat the oven to 350 degrees F (175 degrees C). Grease and flour a 9x5-inch loaf pan.

Beat sugar and margarine in a bowl until smooth. Beat in eggs, then bananas. Add flour and baking soda, stirring just until combined. Pour into the prepared pan.

Bake in the preheated oven until a toothpick in the center comes out clean, about 1 hour. Remove from the pan and let cool.

Store in the refrigerator or freeze.