“Other assets” on our consolidated balance sheets. The balance of pledged securities at December 31, 2006 consisted of $50 million in “Marketable securities” and $86 million in “Other assets”. The amount required to be pledged for certain real estate lease agreements changes over the life of our leases with fluctuations in our market capitalization (common shares outstanding multiplied by the closing price of our common stock) and based on our credit-rating. 

We believe that current cash, cash equivalents, and marketable securities balances will be sufficient to meet our anticipated operating cash needs for at least the next 12 months. However, any projections of future cash needs and cash flows are subject to substantial uncertainty. See Item 1A of Part I, “Risk Factors.” We continually evaluate opportunities to sell additional equity or debt securities, obtain credit facilities from lenders, repurchase common stock, pay dividends, or repurchase, refinance, or otherwise restructure our long-term debt for strategic reasons or to further strengthen our financial position. The sale of additional equity or convertible debt securities would likely be dilutive to our shareholders. In addition, we will, from time to time, consider the acquisition of, or investment in, complementary businesses, products, services, and technologies, which might affect our liquidity requirements or cause us to issue additional equity or debt securities. There can be no assurance that additional lines-of-credit or financing instruments will be available in amounts or on terms acceptable to us, if at all. 

Results of Operations 

We have organized our operations into two principal segments: North America and International. We present our segment information along the same lines that our chief executive reviews our operating results in assessing performance and allocating resources. 

Net Sales and Gross Profit 

Revenue increased 26% in 2006, reflecting revenue growth in both our North America and International segments. Additionally, changes in currency exchange rates positively affected net sales by $24 million for 2006. For a discussion of the effect on revenue growth of exchange rate changes, see “Effect of Exchange Rates” below. 

The North America revenue growth rate was 25% in 2006. This revenue growth primarily reflects increased unit sales driven by our continued efforts to reduce prices for our customers, including from our free shipping offers and Amazon Prime, shift in mix of product sales from media to electronics and other general merchandise, increased in-stock product availability, and increased selection of product offerings in our existing categories. 

The International revenue growth rate was 28% in 2006. This revenue growth reflects increased unit sales driven by our continued efforts to reduce prices for our customers, including from our free shipping offers, shift in mix of product sales from media to electronics and other general merchandise, increased in-stock product availability, and increased selection of product offerings in our existing categories. Additionally, changes in currency exchange rates positively affected International net