to lower of cost or market value. 

We provide fulfillment-related services in connection with certain of our agreements. In those arrangements, as well as other product sales by other sellers, the seller maintains ownership of the related products. As such, these amounts are not included in our consolidated balance sheets. 

Investments 

We generally invest our excess cash in investment grade short- to intermediate-term fixed income securities and AAA-rated money market funds. We also have equity-method investments in private companies where we can exercise significant influence over, but not control, the entity. We periodically evaluate whether declines in fair values of our investments are other-than-temporary. This evaluation consists of several qualitative and quantitative factors regarding the severity and duration of the unrealized loss as well as our ability and intent to hold the investment. Factors considered include, if applicable, quoted market prices; recent financial results and operating trends; other publicly available information; implied values from any recent transactions or offers of investee securities; or other conditions that may affect the value of our investments. 

Goodwill 

We evaluate goodwill for impairment annually and when an event occurs or circumstances change to suggest that the carrying value may not be recoverable. Our annual testing date is October 1. We test goodwill for impairment by first comparing the book value of net assets to the fair value of the related operations. If the fair value is determined to be less than book value, a second step is performed to compute the amount of impairment. We estimate fair value using discounted cash flows of reporting units. Forecasts of future cash flow are based on our best estimate of future net sales and operating expenses, based primarily on projected category expansion, pricing expectations, market segment penetration and general economic conditions. Additionally, certain estimates of discounted cash flows involve businesses and geographies with limited financial history and developing revenue models. In this process, a fair value for goodwill is estimated and compared to its carrying value. The shortfall of the fair value below carrying value represents the amount of goodwill impairment. Changes in these forecasts could significantly change the amount of impairment recorded, if any. 

The 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. 

Internal-Use Software and Website Development 

Included in fixed assets is the capitalized cost of internal-use software and website development, including software used to upgrade and enhance our websites and processes supporting our business. As required by Statement of Position (SOP) 98-1, “Accounting for the Costs of Computer Software Developed or Obtained