There were attempts at airline mergers just before 911. US Airways and United were going to merge but the deal didn't get approved. Both ended up filing bankru

There were attempts at airline mergers just before 911. US Airways and United were going to merge but the deal didn't get approved. Both ended up filing bankruptcy some point later, and since then the airlines have largely merged from a very diverse field into American, Delta, SW and United. The other example is in investment banking - previously the retail and investment banks weren't allowed to merge and many of them got into trouble. Today, after the financial crisis, the industries have consolidated around 4 or 5 major large and broad banks.