Consolidation
The long-run concentration of an industry into fewer, larger owners.
Consolidation is the process by which an industry's many independent producers become a few large owners, through repeated acquisition.
Consumer goods have consolidated heavily since the 1980s. The visible result is that a supermarket aisle showing dozens of competing brands often represents a handful of companies. Measuring it is what category pages here are for: how many brands, how many distinct owners, and what share the largest three hold.