Financial and credit market volatility directly impacts our fair value measurement through
our weighted average cost of capital that we use to determine our discount rate and through our stock price that we use to determine our market capitalization. During times of volatility, significant judgment must be applied to determine whether
credit or stock price changes are a short-term swing or a longer-term trend. As a measure of sensitivity, a prolonged 20% decrease from our December 31, 2012, closing stock price would not be an indicator of possible impairment.
We measure compensation cost for stock awards at fair value and recognize it as compensation expense over the service period for awards expected to vest. The fair value of restricted stock units is
determined based on the number of shares granted and the quoted price of our common stock. The estimation of stock awards that will ultimately vest requires judgment for the amount that will be forfeited, and to the extent actual results or updated
estimates differ from our current estimates, such amounts will be recorded as a cumulative adjustment in the period estimates are revised. We consider many factors when estimating expected forfeitures, including employee class, economic environment,
and historical experience. We update our estimated forfeiture rate quarterly. A 1% change to our estimated forfeiture rate would have had an approximately $22 million impact on our 2012 operating income. Our estimated forfeiture rates at
December 31, 2012 and 2011, were 27% and 28%.
We utilize the accelerated method, rather than the straight-line method,
for recognizing compensation expense. For example, over 50% of the compensation cost related to an award vesting ratably over four years is expensed in the first year. If forfeited early in the life of an award, the compensation expense adjustment
is much greater under an accelerated method than under a straight-line method.
We are subject to income taxes in the U.S. and numerous foreign jurisdictions. Significant judgment is required in evaluating and
estimating our provision and accruals for these taxes. During the ordinary course of business, there are many transactions for which the ultimate tax determination is uncertain. Our effective tax rates could be adversely affected by earnings being
lower than anticipated in countries where we have lower statutory rates and higher than anticipated in countries where we have higher statutory rates, by losses incurred in jurisdictions for which we are not able to realize the related tax benefit,
by changes in foreign currency exchange rates, by entry into new businesses and geographies and changes to our existing businesses, by acquisitions (including integrations) and investments, by changes in the valuation of our deferred tax assets and
liabilities, or by changes in the relevant tax, accounting, and other laws, regulations, administrative practices, principles, and interpretations, with a number of countries actively considering changes in this regard. In addition, we are subject
to audit in various jurisdictions, and such jurisdictions may assess additional income tax liabilities against us. Although we believe our tax estimates are reasonable, the final outcome of tax audits and any related litigation could be materially
different from our historical income tax provisions and accruals. Developments in an audit or litigation could have a material effect on our operating results or cash flows in the period or periods for which that development occurs, as well as for
prior and subsequent periods.
Recent Accounting Pronouncements
See Item 8 of Part II, Financial Statements and Supplementary DataNote 1Description of Business and Accounting
PoliciesRecent Accounting Pronouncements.