Following our election to discontinue accounting for our interest rate swaps as cash flow hedges under GAAP as of September 30, 2011, we extended the terms of our repurchase agreements to reduce the "roll risk" associated with maturing repurchase agreements. As of December 31, 2012, our repurchase agreements had a weighted average original days-to-maturity of 181 days and had a remaining weighted average days-to-maturity of 118 days.
To limit our exposure to counterparty credit risk, we diversify our funding across multiple counterparties and by counterparty region. As of December 31, 2012, we had master repurchase agreements with 32 financial institutions, subject to certain conditions, located throughout North America, Europe and Asia. As of December 31, 2012, less than 4% of our stockholders' equity was at risk with any one repo counterparty, with the top five repo counterparties representing less than 16% of our stockholders' equity. The table below includes a summary of our repurchase agreement funding by number of repo counterparties and counterparty region as of December 31, 2012. For further details regarding our borrowings under repurchase agreements and other debt as of December 31, 2012, please refer to Note 4 to our consolidated financial statements in this Annual Report on Form 10-K.
As of December 31, 2012
Number of Counter-Parties
Percent of Repurchase Agreement Funding
Amounts available to be borrowed under our repurchase agreements are dependent upon lender collateral requirements and the lender’s determination of the fair value of the securities pledged as collateral, which fluctuates with changes in interest rates, credit quality and liquidity conditions within the investment banking, mortgage finance and real estate industries. In addition, our counterparties apply a "haircut” to our pledged collateral, which means our collateral is valued at slightly less than market value. This haircut reflects the underlying risk of the specific collateral and protects our counterparty against a change in its value, but conversely subjects us to counterparty risk and limits the amount we can borrow against our investment securities. Our master repurchase agreements do not specify the haircut; rather haircuts are determined on an individual repurchase transaction basis. Throughout fiscal year 2012, haircuts on our pledged collateral remained stable and as of December 31, 2012, our weighted average haircut was less than 5% of the value of our collateral.
Under our repurchase agreements, we may be required to pledge additional assets to the repurchase agreement counterparties in the event the estimated fair value of the existing pledged collateral under such agreements declines and such counterparties demand additional collateral (a margin call), which may take the form of additional securities or cash. Specifically, margin calls would result from a decline in the value of our agency securities securing our repurchase agreements and prepayments on the mortgages securing such agency securities. Similarly, if the estimated fair value of our investment securities increases due to changes in interest rates or other factors, counterparties may release collateral back to us. Our repurchase agreements generally provide that the valuations for the agency MBS securing our repurchase agreements are to be obtained from a generally recognized source agreed to by the parties. However, in certain circumstances under certain of our repurchase agreements our lenders have the sole discretion to determine the value of the agency MBS securing our repurchase agreements. In such instances, our lenders are required to act in good faith in making such valuation determinations. Our repurchase agreements generally provide that in the event of a margin call, we must provide additional securities or cash on the same business day that a margin call is made if the lender provides us notice prior to the margin notice deadline on such day.
As of December 31, 2012, we have met all of our margin requirements and we had unrestricted cash and cash equivalents of $2.4 billion and unpledged agency securities of $3.7 billion available to settle our net payable for agency securities, meet margin calls on our repurchase agreements and derivative instruments and for other corporate purposes.
Although we believe we will have adequate sources of liquidity available to us through repurchase agreement financing to execute our business strategy, there can be no assurances that repurchase agreement financing will be available to us upon the maturity of our current repurchase agreements to allow us to renew or replace our repurchase agreement financing on favorable terms or at all. If our repurchase agreement lenders default on their obligations to resell the underlying agency securities back to us at the end of the term, we could incur a loss equal to the difference between the value of the agency securities and the cash we originally received.