Comment by wavemode

A stock exchange is nothing more than a marketplace. Anyone can start their own (the challenge being, getting a bunch of companies to want to list their stock with you).

That freedom is actually why it's hard to create a Bloomberg competitor - in order to provide their data stream, Bloomberg has to have partnerships with hundreds of companies worldwide who run exchanges for stocks, bonds and other instruments. If exchanges were government-controlled rather than free-market, there would be more centralization and getting the data together would be easier.