In the real world, the forces for increasing and decreasing returns to scale often operate side by side, with the forms prevailing at small levels of output (so that the LAC curve declines ) and the later tending to prevail at small levels of output (so that the LAC curve rises ). The lowest point on the LAC curve occurs when the forces for increasing and decreasing returns to scale just balance each other. In the real world, however, the LAC curve is often found to have a nearly flat bottom and to be L-shaped rather than U-shaped. This implies that economies of scale are rather quickly exhausted and constant or near constant returns to scale prevail over a considerable range of output in many industries. In these industries, small firms coexist with much larger firms.