Interestingly, present cash flow and profit are generally not relevant when taking over a business that can be perfectly integrated with your current business (as was the case with IB). IB knows, based on their experience, how much they earn per page view. Times that by the page views of the takeover target and you have the expected earnings. That the current site is (likely) earning less than that isn't important as it's based on a revenue/cost basis that isn't going to be retained.