Which is why we got the Sherman Antitrust Act during the last gilded age. Odds are we won't get one this time around though, as our democratic institutions have been completely defanged in the name of "pro business".

It is also almost always bad for shareholders when companies are merged.

Let's say there are two competing companies, I could myself as an investor chose where to put my money, in one or the other or both. When they merge I lose the ability to place my money how I see fit.

As my professor/dean in financial economics said: If you get to vote on a merger, always vote no!

This seems to assume that the conjoined entity is exactly equivalent in terms of efficiency and market power to the previous two separate entities- That's a pretty radical assumption and it seems you'd have to give some evidence to explain why this would be the case.

I don't have any evidence other than anecdotal and theories.

I used to work in a bank that merged with another and the amount of inefficiencies, double teams/management and general disgruntlement was staggering. I left and so did most of the ones capable of finding new jobs. The ones that stayed behind were not the highest performers.

Another one is from macro economics. When two companies compete they tend to be very efficient but when they merge they have no more incentives to compete to attract customers. The result is higher prices to customers and lower effectiveness. Imagine what would happen if Intel bough AMD.

But the main issue is that I want to manage my investments myself and not let the companies manage it for me by merging.