We passed the Sherman Anti Trust Act back in the 1890's. It was used to break up Standard Oil in the early 20th century, and last used to break up the telephone company in the 1960's. The Sherman act gives the US government the right to break up big companies that are deemed monoplistic, or just too damn big. It's still on the books and the US Justice Dept has a whole division of lawyers to enforce it. Too bad they haven't been earning their pay.
At the beginning of Great Depression 2.0 it was decided to drop Lehman Brothers on the floor as a warning to others. Not a bad idea, but the breakage scared everybody. Soon after, Sec of Treasury Paulson and Chairman of the Fed Bernanke, both thoroughly frightened, went to Congress and got the $800 billion TARP bill passed to shore up the rest of the Wall St to avoid more breakage. Then the perpetrators of Great Depression 2.0, Congress critters Barney Frank and Chris Dodd, got the 2000 page Dodd Frank bill passed to guarantee US taxpayer bailout of "too big to fail" financial institutions.
Where are the anti trust lawyers? Any firm "Too Big To Fail" is clearly big enough to break up under the Sherman Anti Trust act.
Plus, big firms lack competition to keep their pricing honest. We consumers get robbed anytime a company is so big it is the only game in town.