Security exchange market?

[my world is different]

What are the advantages and disadvantages of having a single security exchange market in a country?
Also, what could be the effects of the monopoly of such market?

[zuma]

disadvantages,...It couldn't handle traffic in major market moves,..They couldn't even handle Facebook, much less a serious Market correction..
Corruption,...Skimming fractional gains, with the help of algorithm computer to computer trading, ..and able to shuffle the Bids, and Ask, Prices.(I'm guessing)..An Illegal account for the firm,.. got preferential treatment..or anyone else in on the Scam..

More than one exchange creates competition,...and keeps them honest..(Libor Scandal)

Natural, or man-made disasters,..Cantor Fitzgerald was wiped out completely, when the World Trade buildings collapsed..Except for those employees that walked out..

advantages,...none ...that justify the faults..It's a Crook that would promote a monopoly..or deregulation