NYX, NDAQ, CME, X.TO etc
Remortgaging a house to invest in stock market is very risky unless one has guaranteed future cash flow.
I happened to have studied the stock exchanges a few years ago. I think it is worthwhile to go through 10K's of these companies in order to gain insight of economics (and thus long-term return) of exchange companies.
Based on my amateur understanding, pure stock exchanges depend on trading volume and listing for revenue and profit. Trading is very competitive from electronic trading systems and thus the profit was not really high (when I looked at NDAQ a few years ago). Listing is more stable but there is always regulation concerns in that more listings are allowed (as in the recent case in Australia).
CME is able to command a high P/E due to its role in derivative trading. Unlike stock trading, derivative trading is hard to move around. However, I personally don't really know the true competitive edge of CME etc ...
Just my few cents for references ... Again, I am just an amateur and don't really have professional expertise ...