the Wyeth acquisition, partially offset by cash flows from operations.

Credit Ratings

Two major corporate debt-rating organizations, Moody’s Investors Service (Moody’s) and Standard & Poor’s (S&P), assign ratings to our short-term and long-term debt. The following chart reflects the current ratings assigned by these rating agencies to our commercial paper and senior unsecured non-credit-enhanced long-term debt issued by us:

COMMERCIAL LONG-TERM DEBT

DATE OF LAST ACTION

October 2009 October 2009

    We have available lines of credit and revolving credit agreements with a group of banks and other financial intermediaries. We maintain cash and cash equivalent balances and short-term investments in excess of our commercial paper and other short-term borrowings. As of December 31, 2010, we had access to $9.0 billion of lines of credit, of which $1.9 billion expire within one year. Of these lines of credit, $8.4 billion are unused, of which our lenders have committed to loan us $7.0 billion at our request. Also, $7.0 billion of our unused lines of credit, all of which expire in 2013, may be used to support our commercial paper borrowings.

Global Economic Conditions

The challenging economic environment has not had, nor do we anticipate it will have, a significant impact on our liquidity. Due to our significant operating cash flow, financial assets, access to capital markets and available lines of credit and revolving credit agreements, we continue to believe that we have the ability to meet our liquidity needs for the foreseeable future. As markets change, we continue to monitor our liquidity position. There can be no assurance that the challenging economic environment or a further economic downturn would not impact our ability to obtain financing in the future.

Selected Measures of Liquidity and Capital Resources

The following table sets forth certain relevant measures of our liquidity and capital resources:

The increase in cash and cash equivalents and short-term investments and loans, as of December 31, 2010, compared to December 31, 2009, was primarily due to operating cash flows, partially offset by the use of proceeds of short-term investments for repayment of short-term borrowings and for tax payments made in 2010, associated mainly with certain business decisions executed to finance the Wyeth acquisition. The change in working capital and the ratio of current assets to current liabilities was due to the timing of accruals, cash receipts and payments in the ordinary course of business. We are monitoring developments regarding government receivables in several European markets. Where necessary, we will continue to adjust our allowance for doubtful accounts.

We funded our business-development transactions that closed in the fourth quarter of 2010 with available cash and the proceeds from short-term investments, and we did the same in connection with the completion of our tender offer for the shares of King in January 2011. For additional information about these transactions, see the “Our Business Development Initiatives” section of this Financial Review.

Summary of Cash Flows

Operating Activities

2010 vs. 2009

Our net cash