(2) Operating Income is a non-GAAP financial measure. Operating income is an internal performance measure used by Aspen in the management of its operations and represents after-tax operational results excluding, as applicable, after-tax net realized and unrealized capital gains or losses, including net realized and unrealized gains or losses on interest rate swaps, and after-tax net foreign exchange gains or losses, including net realized and unrealized gains and losses from foreign exchange contracts.
Aspen excludes these items from its calculation of operating income because the amount of these gains or losses is heavily influenced by, and fluctuates in part, according to the availability of market opportunities. Aspen believes these amounts are largely independent of its business and underwriting process and including them would distort the analysis of trends in its operations. In addition to presenting net income determined in accordance with GAAP, Aspen believes that showing operating income enables investors, analysts, rating agencies and other users of its financial information to more easily analyze Aspen's results of operations in a manner similar to how management analyzes Aspen's underlying business performance. Operating income should not be viewed as a substitute for GAAP net income. Please see above and page 23 of Aspen's financial supplement for a reconciliation of operating income to net income. Aspen’s financial supplement can be obtained from the Investor Relations section of Aspen's website at www.aspen.co.
(3) Diluted Book Value per Ordinary Share is not a non-GAAP financial measure. Aspen has included diluted book value per ordinary share as it illustrates the effect on basic book value per share of dilutive securities thereby providing a better benchmark for comparison with other companies. Diluted book value per share is calculated using the treasury stock method, defined on page 22 of Aspen’s financial supplement, which can be obtained from the Investor Relations section of Aspen’s website at www.aspen.co.
(4) Diluted Operating Earnings per Share and Basic Operating Earnings per Share are non-GAAP financial measures. Aspen believes that the presentation of diluted operating earnings per share and basic operating earnings per share supports meaningful comparison from period to period and the analysis of normal business operations. Diluted operating earnings per share and basic operating earnings per share are calculated by dividing operating income by the diluted or basic weighted average number of shares outstanding for the period. See page 23 for a reconciliation of diluted and basic operating earnings per share to basic earnings per share. Aspen’s financial supplement can be obtained from the Investor Relations section of Aspen’s website at www.aspen.co.(5) Combined Ratio Excluding Catastrophes is a non-GAAP financial measure. Aspen believes that the presentation of combined ratio excluding catastrophes supports meaningful comparison from period to period of the underlying performance of the business. Combined ratio excluding catastrophes is calculated by dividing net losses excluding catastrophe losses and net expenses by net earned premiums excluding catastrophe related reinstatement premiums. We have defined 2012 catastrophe losses as losses associated with the severe weather in the US in February and March 2012, Hurricane Isaac in August 2012 and Hurricane Sandy in October 2012 and movements in losses associated with the 2011 catastrophe events. We have defined catastrophe losses in the comparative period as losses associated with the US storms (specifically related to Hurricane Irene which occurred in the third quarter of 2011, and related to the tornadoes which occurred in the second quarter of 2011), the Australian floods and the New Zealand and Japanese earthquakes which occurred in the first quarter of 2011, and movement in losses associated with the 2010 catastrophe events (Chilean and New Zealand earthquakes) which were recognized in 2011. Other (1) Provision of ASU 2010-26. In 2012, Aspen adopted the provision of ASU 2010-26, “Accounting for Costs Associated with Acquiring or Renewing Insurance Contracts.” Under the standard, Aspen is required to expense the proportion of its general and administrative deferred acquisition costs not directly related to successful business acquisition. The application of this standard has resulted in a net $16.0 million write down of deferred acquisition costs through retained earnings brought forward and the restatement of our quarterly balance sheets from December 31, 2010 to December 31, 2011. (2) Catastrophe Load included in our guidance is an estimate of the average annual aggregate loss before reinsurance and tax from natural catastrophe events based on 50,000 simulations of our internal capital model which, in relation to its catastrophe modeling components, is based on a combination of catastrophe models selected by Aspen to best fit its current understanding of the world wide natural catastrophe perils to which Aspen has known exposures. It does not include losses from non-natural catastrophe events such as terrorism or industrial accidents. This load is attributed and then released quarter by quarter based on historic claims patterns. For example, there is a higher proportion allocated to the third quarter due to the historical frequency of US Wind events in this period. As an organization, Aspen monitors its current catastrophe losses to date against expected losses and updates the projected numbers accordingly based on this experience.