So, there are anti-trust laws in the US. This limits the size of companies based on market share. The goal of this is to limit monopolies. Capitalism is a great

So, there are anti-trust laws in the US. This limits the size of companies based on market share. The goal of this is to limit monopolies. Capitalism is a great system at responding to market conditions and efficiently allocating resources. Capitalism is less effective when monopolies form, and it causes the business cycle which can be unpleasant and disruptive for the people participating in the economy. Source -- I am an armchair internet economist.