MFA generated fourth quarter net income of $35.9 million, or $0.08 per common share.
GAAP book value at December 31, 2021 was $4.78 per common share, while Economic book value, a non-GAAP financial measure of MFA's financial position that adjusts GAAP book value by the amount of unrealized market value changes in residential whole loans and securitized debt held at carrying value for GAAP reporting, was $5.15 per common share at quarter-end.
Net interest income increased on a sequential quarterly basis to $70.1 million, primarily driven by continued successful asset acquisitions and another record quarter for origination volumes at Lima One, resulting in a 13% increase in net interest income.
In addition, during the quarter, we completed a securitization of $284.2 million of Single-Family Rental Loans, with a weighted average coupon of bonds sold of 2.15%, providing $103.1 million additional liquidity and longer term, non-recourse, non-mark-to-market financing. We also completed two securitizations of Agency Eligible Single-Family Rental loans totaling $652.9 million during the quarter. For the fourth quarter, the overall net interest spread generated by all of our interest-bearing assets was 2.98%, unchanged from the prior quarter.
Loan acquisition activity of $1.4 billion reflects continued successful execution of our asset aggregation strategy, resulting in net portfolio growth for the quarter approaching $800 million. During the quarter we acquired, or committed to acquire, approximately $950 million of Non-QM loans.
At Lima One, funded originations were more than $450 million (over $600 million maximum loan amount inclusive of undrawn amounts), reflecting record volumes for the second consecutive quarter. In addition, draws funded during the quarter on Rehabilitation loans were $45.7 million. For the full year, MFA acquired approximately $4.6 billion in residential whole loans (including draws on Rehabilitation loans), resulting in net portfolio growth of $2.6 billion.
Interest rate volatility resulted in market value decreases in our residential whole loans that are measured at fair value through earnings of $42.6 million. These unrealized losses reflect a partial reversal of unrealized gains recorded in earlier quarters of 2021.
On a full year basis we recorded unrealized gains on these loans of $16.2 million. ■