Our focus will continue to be in high quality assets as the vast majority of our assets are agency MBS, which are liquid and financeable.
To effect this change in leverage strategy, we have, since Friday, March 7, 2008, sold approximately $1 billion in MBS. The assets sold consist of approximately $950 million of agency MBS and $50 million of AAA-rated non- agency MBS at a realized loss of approximately $15 million. Concurrently, we have terminated repurchase agreements at no cost and approximately $525 million of associated interest rate swap agreements at a cash cost of approximately $31 million.
We have made this strategy adjustment because it is our view that credit conditions are tightening, rapidly and indiscriminately. After analyzing recent credit events impacting other leveraged public and private companies investing in high quality MBS, we believe that while these companies utilized substantially higher levels of leverage than MFA, our interpretation of their public disclosure and other information available to us increases the probability of increased margin requirements in the future for all repurchase agreement borrowers, including MFA. Additionally, recent news about potential security liquidations has increased our concerns about declining values for many financial assets including agency and AAA-rated MBS. As a result, we have proactively reduced leverage to decrease the potential negative impact of increased margin requirements and falling asset values.
We currently estimate our book value per share to be in the range of $5.75-$6.00. As of tonight, March 10, 2008, MFA's available cash balance totaled approximately $348 million and our unpledged agency MBS had a valueof approximately $19 million, both of which are available to meet future margin calls. To date, MFA has satisfied all of its margin calls.
On a positive note, while we will be generally utilizing lower levels of leverage, the spread MFA expects to earn on its assets is expected to increase in 2008. Excluding the realized losses from asset sales and swap terminations, based on current estimates, we expect MFA's earnings will approximate $0.18 per share of common stock in the first quarter of 2008 versus $0.16 per share in the fourth quarter of 2007.
We have undertaken these actions to decrease potential future liquidity risks. We believe that while many financial institutions may face the risk of systemic margin calls, our strategy is to get ahead of the curve and reduce leverage consistent with our own discipline. We believe this strategy will reduce the uncertainty reflected in MFA's share price and will allow MFA to be positioned to take advantage of the many profitable opportunities that we believe will be available in the future. -- MFA Mortgage Investments, Inc.
