The following table summarizes the carrying amount of our borrowings under various financing arrangements (in thousands):

In March 2011, we issued the 2021 Notes in a registered offering for an aggregate principal amount of $1.00 billion. The 2021 Notes will mature on April 1, 2021 and pay interest at a fixed annual rate of 4.50%. Debt issuance costs incurred in connection with the issuance of this debt totaled approximately $5.8 million and are being amortized to interest expense over the contractual term of the 2021 Notes.

The 2021 Notes may be redeemed at our option at any time or from time to time, at a redemption price equal to the greater of (i) 100% of the principal amount of the notes to be redeemed and (ii) the sum, as determined by an independent investment banker, of the present values of the remaining scheduled payments of principal and interest on the notes to be redeemed (exclusive of interest accrued to the date of redemption) discounted to the redemption date on a semiannual basis at the Treasury Rate plus 20 basis points, plus, in each case, accrued and unpaid interest on the notes to be redeemed to the date of redemption. At any time on or after January 1, 2021, we may redeem the notes, in whole or in part, at 100% of the principal amount of the notes to be redeemed, plus accrued and unpaid interest to the date of redemption. In addition, in the event of the occurrence of both a change in control and a downgrade in the rating of the 2021 Notes below an investment grade rating by Standard & Poor's Ratings Services and Moody's Investors Service, Inc., the holders may require us to purchase all or a portion of their notes at a price equal to 101% of their principal amount, plus accrued and unpaid interest.

We expect to use the net proceeds for general corporate purposes, which include the repayment of existing indebtedness and repurchases of our common stock.

In May 2011, our 2011 Notes matured and we repaid the aggregate principal balance of $650.0 million. We also paid $36.1 million in cash related to the conversion spread of the 2011 Notes, which represents the conversion value in excess of the principal amount, and received $36.1 million in cash from our convertible note hedges related to the 2011 Notes. Warrants related to our 2011 Notes expired in August 2011.

Under our amended and restated credit agreement, we, along with our wholly-owned subsidiary, Gilead Biopharmaceutics Ireland Corporation, may borrow up to an aggregate of $1.25 billion in revolving credit loans. The credit agreement also includes a sub-facility for swing-line loans and letters of credit. Loans under the credit agreement bear interest at an interest rate of either LIBOR plus a margin ranging from 20 basis points to 32 basis points or the base rate, as described in the credit agreement. We may reduce the commitments and may prepay loans under the credit agreement in whole or in part at any time without penalty, subject to certain conditions. The credit agreement will terminate in December 2012 and all unpaid borrowings thereunder shall be due and payable at that time. As of September 30, 2011, we had $2.4 million in letters of credit outstanding under the $1.25 billion credit agreement. We are required to comply with certain covenants under the credit agreement and as of September 30, 2011, we were in compliance with all such covenants.