Critical Accounting Estimates

Revenue from Initial and Additional listing fees

We recognize revenue generated from initial and additional listing fees on a straight line basis over an estimated service period of ten years. The estimated service period of ten years was determined by conducting an historical review of listing activity. We determined that the average period of time that an issuer remained listed on Toronto Stock Exchange was approximately ten years. In addition, turnover rates were calculated for a Toronto Stock Exchange listed issuer and for a TSX Venture Exchange listed issuer and were determined to be in the range of ten to twelve years. Examining historical data allowed us to consider the impact of economic cycles and other trends in capital markets over time. The service period selected affects the rate at which deferred revenue is recognized, as well as the value of the future tax asset related to these fees.

Long-term Incentive Plan

We have a long-term incentive plan under which we may grant RSUs. RSUs vest on December 31 of the second calendar year following the year in which the RSUs were granted and the cash award payable is determined by the total shareholder return (appreciation in share price plus dividends paid or TSR) at the end of that period. We accrue our obligations and include them in accounts payable and accrued liabilities and other liabilities. In prior years, these obligations were estimated and recorded at a targeted payout amount which was not necessarily based on the maximum amount that might be paid. The maximum amount to be paid is not known until the RSUs have vested and will be based on TSR at the time of payout. Effective January 1, 2007, we changed our estimate of these obligations. Our accrual is based on actual dividends paid, continuation of the most recent quarterly dividend and the closing share price of our common shares for the period. Having monitored fluctuations in our share price, we concluded that accruing our obligations in this manner provided a better estimate of the payout compared with an estimate based on a target. The impact of this change in methodology for making the estimate was to increase these obligations and compensation and benefits costs by $1.1 million for 2007. We have purchased derivative financial instruments that partially hedge the impact of our share price appreciation.

Impairment of Goodwill and Intangible Assets

As required by CICA Handbook Section 3062 Goodwill and other Intangible Assets and Section 3063 Impairment of long-lived assets, we performed impairment tests on our reporting units to determine whether our reporting units or their assets could be impaired. The tests required us to make assumptions regarding projected cash flows, including long-term growth rates, for the various reporting units. The tests also required us to apply a discount rate based on our risk adjusted cost of capital. These assumptions are subjective judgments based on our experience, knowledge of operations and knowledge of the economic environment in which we operate. It is possible that, if future cash flow projections or discount rates are significantly different to those used, the outcome of future impairment tests could result in some or all of our reporting units and their associated goodwill and intangible assets being impaired.