On a GAAP basis, noninterest income of $91.8 million declined $10.4 million from the prior quarter. Prior quarter results included a $5.3 million gain recognized on the sale of $3.1 billion in CMOs in the second quarter.
Fourth quarter non-GAAP operating noninterest expenses were $235.1 million, decreasing $2.0 million, or 1%, compared to the third quarter, driven by the initial impact of the company's workforce optimization initiative in the third quarter. The benefit of the resulting $4.5 million decrease in salaries and benefits was minimized by seasonal increases in occupancy expenses. Excluding the additional $3.4 million in additional premium amortization recognized in the fourth quarter, the efficiency ratio of 64.6% was comparable to 64.7% in the prior quarter.
On a GAAP basis, noninterest expense for the fourth quarter was $238.8 million, including $3.7 million in restructuring charges.Capital At December 31, 2012, the company's estimated consolidated Total Risk Based capital and Tier 1 Common Risk Based capital ratios were 11.2% and 7.5% respectively. The company remains well above current regulatory guidelines for well-capitalized institutions. About First Niagara First Niagara, through its wholly owned subsidiary, First Niagara Bank, N.A., is a multi-state community-oriented bank with approximately 430 branches, approximately $37 billion in assets, $28 billion in deposits, and approximately 6,000 employees providing financial services to individuals, families and businesses across Upstate New York, Pennsylvania, Connecticut and Massachusetts. For more information, visit www.firstniagara.com . Investor Call A conference call will be held at 8:30 a.m. Eastern Time on Wednesday, January 23, 2013 to discuss the company's financial results. Those wishing to participate in the call may dial toll-free 1-888-324-9650 with the passcode: FNFG. Presentation slides will be used during the earnings conference call and is available under the investor relations tab of our website at www.firstniagara.com . A replay of the call will be available until February 6, 2013 by dialing 1-888-566-0438, passcode: 15645. Non-GAAP Measures - This news release contains financial information determined by methods other than in accordance with accounting principles generally accepted in the United States of America (GAAP). The Company believes that non-GAAP financial measures provide a meaningful comparison of the underlying operational performance of the company, and facilitate investors' assessments of business and performance trends in comparison to others in the financial services industry. In addition, the company believes the exclusion of these non-operating items enables management to perform a more effective evaluation and comparison of the company's results and to assess performance in relation to the company's ongoing operations. These disclosures should not be viewed as a substitute for financial measures determined in accordance with GAAP, nor are they necessarily comparable to non-GAAP performance measures that may be presented by other companies. Where non-GAAP disclosures are used in this news release, the comparable GAAP financial measure, as well as the reconciliation to the comparable GAAP financial measure, can be found in this document.