Utilize your financial knowledge, give your answer or opinion to the input question or subject . Answer format is not limited.

Are large companies more profitable than small ones?
There is no general theory to support the notion that larger companies will be more profitable than smaller companies.  Economies of scale are not always positive, one can have diseconomies of scale too.   It is more common to talk about an optimal firm size, even going back to Stigler's (1958) "The Economies of Scale."  Intuitively, if economies of scale extended indefinitely, then natural monopolies would dominate all industries in the long run. A profit ratio, unfortunately, wouldn't quite get at scale economies.  Consider, for example, that the denominator of your metric would be profit+cost and that you are trying to get at the cost reduction that derives from scale.  Then, you are measuring the size of a company by the exact metric that should be reduced if scale economies exist, so the calculation would be a bit confounded. It is my understanding that such assessments are usually conducted at the industry level by determining whether the industry is becoming increasingly concentrated among fewer firms over time. (Again see Stigler).   If concentration is increasing, there is an implication that, at current firm sizes, there are economies of scale in the industry.