in 2010 and 2011. 

Equity–Method Investment Activity, Net of Tax 

Equity–method investment gains (losses), net of tax, were $(12) million, $7 million, and $(6) million in 2011, 2010, and 2009. The increase in equity-method investment activity in 2011 compared to 2010 is primarily due to $175 million of equity-method losses, partially offset by gains of $163 million as a result of reductions in our equity ownership, through dilution, and a recovery on the sale of an equity position. The increase in equity-method investment activity in 2010 compared to 2009 is primarily due to the recognition of a non-cash gain on a previously held equity position in a company that was acquired in 2010. 

Non-GAAP Financial Measures 

Regulation G, Conditions for Use of Non-GAAP Financial Measures, and other SEC regulations define and prescribe the conditions for use of certain non-GAAP financial information. Our measures of “Free cash flow,” operating expenses with and without stock-based compensation, and the effect of exchange rates on our consolidated statement of operations, meet the definition of non-GAAP financial measures. 

Free cash flow is used in addition to and in conjunction with results presented in accordance with GAAP and free cash flow should not be relied upon to the exclusion of GAAP financial measures. 

Free cash flow, which we reconcile to “Net cash provided by (used in) operating activities,” is cash flow from operations reduced by “Purchases of fixed assets, including internal-use software and website development.” We use free cash flow, and ratios based on it, to conduct and evaluate our business because, although it is similar to cash flow from operations, we believe it typically will present a more conservative measure of cash flows since purchases of fixed assets are a necessary component of ongoing operations. 

Free cash flow has limitations due to the fact that it does not represent the residual cash flow available for discretionary expenditures. For example, free cash flow does not incorporate the portion of payments representing principal reductions of obligations related to capital leases and leases accounted for as financing arrangements or cash payments for business acquisitions. Therefore, we believe it is important to view free cash flow as a complement to our entire consolidated statements of cash flows. 

Operating expenses with and without stock-based compensation is provided to show the impact of stock-based compensation, which is non-cash and excluded from our internal operating plans and measurement of financial performance (although we consider the dilutive impact to our shareholders when awarding stock-based compensation and value such awards accordingly). In addition, unlike other centrally-incurred operating costs, stock-based compensation is not allocated to segment results and therefore excluding it from operating expense is consistent with our segment presentation in our footnotes to the consolidated financial statements. 

Operating expenses without stock-based compensation has limitations since it does not include all expenses primarily related to our workforce. More specifically, if we did not pay out a