In addition, mergers between advertisers could be a source of conflict-of-interest problems: for example, when the ad agency of an acquired company also provided services to a firm that competed with the client in another product category.
Silk explores this problem in his 2012 paper, Conflict Policy and Advertising Agency-Client Relations: The Problem of Competing Clients Sharing a Common Agency.
Since Don Draper's time, the advertising industry has gone through—and might not be done yet with—a major restructuring.
Technology, globalization, government intervention, and a shift away from reliance on mass markets have changed the environment in which advertisers, media, and agencies operate.
Among other things, the system supported standards for granting of credit to agencies and established a fixed commission rate paid by magazine and newspaper publishers to agencies. Davis detail in The Unbundling of Advertising Agency Services: An Economic Analysis, agencies continued to bundle their advertising services and collect media commissions for decades.
That practice finally started to change in the 1980s.
The essential idea was to operate two or more agencies (or "networks" of specialized service agencies) under common ownership as quasi-independent entities.
But since the mid-1980s, waves of mergers and acquisitions have created potential conflicts of interest as independent agencies that were separately serving competing clients suddenly came under common ownership.
That makes sense, says Silk, since a range of factors favor a highly diverse and geographically dispersed industry, especially low-entry costs and limited economies of scale.
The advertising business continues to attract creative talent who form and staff small, nimble firms, all the while perpetuating a diverse and highly competitive industry structure.