SECURITIES AND EXCHANGE COMMISSION

þ QUARTERLY REPORT UNDER SECTION 13 OR 15 (d)
OF THE SECURITIES EXCHANGE ACT OF 1934

FOR THE QUARTERLY PERIOD ENDED
March 31, 2005

COMMISSION FILE NUMBER 0-10161

FIRSTMERIT CORPORATION

III CASCADE PLAZA, 7TH FLOOR, AKRON, OHIO
44308-1103
(Address of principal executive offices)

(330) 996-6300
(Telephone Number)

     Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15 (d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. YES þ NO o

     Indicate by check mark whether the registrant is an accelerated filer (as defined in Rule 12b-2 of the Exchange Act). YES þ NO o

     As of April 30, 2005, 83,618,140 shares of the registrant’s common stock, without par value, were outstanding.

Table of Contents

PART I — FINANCIAL INFORMATION

ITEM 1. FINANCIAL STATEMENTS

FIRSTMERIT CORPORATION AND SUBSIDIARIES
CONSOLIDATED BALANCE SHEETS

The accompanying notes are an integral part of the consolidated financial statements.

FIRSTMERIT CORPORATION AND SUBSIDIARIES
CONSOLIDATED STATEMENTS OF INCOME AND COMPREHENSIVE INCOME

The accompanying notes are an integral part of the consolidated financial statements.

CONSOLIDATED STATEMENTS OF CASH FLOWS
FIRSTMERIT CORPORATION AND SUBSIDIARIES

The accompanying notes are an integral part of the consolidated financial statements.

FirstMerit Corporation and Subsidiaries
Notes to Consolidated Financial Statements
March 31, 2005 (Unaudited) (Dollars in thousands)

1. Company Organization and Financial Presentation — FirstMerit Corporation (“Corporation”), is a bank holding company whose principal asset is the common stock of its wholly owned subsidiary, FirstMerit Bank, N. A. The Corporation’s other subsidiaries include Citizens Savings Corporation of Stark County, FirstMerit Capital Trust I, FirstMerit Community Development Corporation, FirstMerit Credit Life Insurance Company, FMT, Inc., SF Development Corp and Realty Facility Holdings XV, L.L.C.

     The consolidated balance sheet at December 31, 2004 has been derived from the audited consolidated financial statements at that date. The accompanying unaudited interim financial statements reflect all adjustments (consisting only of normally recurring accruals) that are, in the opinion of management, necessary for a fair statement of the results for the interim periods presented. Certain information and note disclosures normally included in financial statements prepared in accordance with accounting principles generally accepted in the United States of America have been omitted in accordance with the rules of the Securities and Exchange Commission (“SEC”). The consolidated financial statements of the Corporation as of March 31, 2005 and 2004 are not necessarily indicative of the results that may be achieved for the full fiscal year or for any future period. These unaudited consolidated financial statements should be read in conjunction with the audited consolidated financial statements for the fiscal year ended December 31, 2004.

     Certain previously reported amounts have been reclassified to conform to the current reporting presentation.

2. Recent Accounting Pronouncements — On September 30, 2004, the Emerging Issues Task Force (“EITF”) of Financial Accounting Standard Board (“FASB”) issued a final FASB Staff Position, FSP EITF Issue 03-1-1, which delayed the effective date for the measurement and recognition guidance included in EITF Issue 03-1 which prescribed the criteria that should be used to determine when an investment is considered impaired, whether that impairment is other than temporary, and the measurement of an impairment loss. The disclosures about unrealized losses that have not been recognized as other-than-temporary impairments have not been deferred and appear in Footnote 4 (Investment Securities) of the 2004 Form 10-K.

     In December 2003, the American Institute of Certified Public Accountants issued Statement of Position 03-3 (“SOP 03-3”) “Accounting for Certain Loans of Debt Securities Acquired in a Transfer.” SOP 03-3 requires acquired loans, including debt securities, to be recorded at the amount of the purchaser’s initial investment and prohibits carrying over valuation allowances from the seller for those individually-evaluated loans that have evidence of deterioration in credit quality since origination, and it is probable all contractual cash flows on the loan will be unable to be collected. SOP 03-3 also requires the excess of all undiscounted cash flows expected to be collected at acquisition over the purchaser’s initial investment to be recognized as interest income on a level-yield basis over the life of the loan. The guidance is effective for loans acquired in fiscal years beginning after December 15, 2004 and is not

expected to have a material impact on the Corporation’s financial condition, results of operations, or liquidity.

     In December 2002, the FASB issued SFAS No. 148, “Accounting for Stock-Based Compensation – Transition and Disclosure.” SFAS No. 148 is an amendment of SFAS No. 123 (“Accounting for Stock-Based Compensation”) and provides alternative methods of transition for a voluntary change to the fair value based method of accounting for stock-based employee compensation. SFAS No. 148 also requires prominent disclosures in both annual and interim financial statements about the method of accounting for stock-based employee compensation and the effect of the method used on reported results. The Corporation currently accounts for stock-based employee compensation under the provisions of Accounting Principles Board (“APB”) No. 25 “Accounting for Stock Issued to Employees” and related interpretations. No stock based employee compensation cost is reflected in net income, as all options granted under those plans had an exercise price equal to the market value of the underlying common stock on the date of grant. The following table illustrates the effect on net income and earnings per share if the Corporation had applied the fair value recognition provisions of SFAS No. 123 to stock based employee compensation. The Black-Scholes option-pricing model was used to estimate the fair market value of the options at the date of grant. This model was originally developed for use in estimating the fair value of traded options, which have different characteristics from the Corporation’s employee stock options. The model is also sensitive to changes in subjective assumptions, which can materially affect fair value estimates.

     In December 2004, the FASB issued a revision of SFAS No. 123, Accounting for Stock-Based Compensation (“SFAS 123R”). This statement superseded APB Opinion No. 25 and its related guidance. SFAS 123R requires companies to expense the fair value of employee stock options and is effective for the first fiscal quarter beginning after June 15, 2005. On April 14, 2005 the SEC adopted a new rule that would extend the compliance date until the first quarter of 2006. Management plans to adopt SFAS 123R effective January 1, 2006 and is presently analyzing the alternative transition methods and option pricing models that are available under the new standard.

     In December 2003, President Bush signed the Medicare Prescription Drug, Improvement and Modernization Act of 2003 (“Modernization Act”), which introduces a prescription drug benefit under Medicare, into law. On May 19, 2004, FASB issued FASB Staff Position FAS No. 106-2, “Accounting and Disclosure Requirements Related to the Medicare Prescription Drug, Improvement and Modernization Act of 2003” (“FSP FAS No. 106-2”) which provides guidance on accounting for the effects of the new Medicare prescription drug legislation by employers whose prescription drug benefits are actuarially equivalent to the drug benefit under Medicare Part D. The Corporation early adopted this FSP in the first quarter of 2004 and has recognized the effect of the Modernization Act in the calculation of its postretirement benefit liability as of January 1, 2004. This change is more fully described in Note 10 (Benefit Plans) of these consolidated financial statements.

3. Critical Accounting Policies — The accounting and reporting policies of the Corporation are in accordance with accounting principles generally accepted within the United States of America and conform to general practices within the banking industry. Accounting and reporting policies for the allowance for loan losses, income taxes, mortgage servicing rights, derivative instruments and hedging activities, and pension and postretirement benefits are deemed critical since they involve the use of estimates and require significant management judgments. Application of assumptions different than those used by management could result in material changes in the Corporation’s financial position or results of operations. Note 1 (Summary of Significant Accounting Policies) and Note 4 (Allowance for Loan Losses), as described in the 2004 Form 10-K, provide considerable detail with regard to the Corporation’s methodology and reporting of the allowance for loan losses. Additional information for income tax accounting is contained within Note 1, as well as in Note 11 (Federal Income Taxes) as described in the 2004 Form 10-K. Accounting for mortgage servicing rights was also discussed in the 2004 Form 10-K in Note 1 and Note 6 (Mortgage Servicing Rights and Mortgage Servicing Activity). Derivative instruments and hedging activities are described more fully in Note 9 (Accounting for Derivatives) in these consolidated financial statements, as well as Note 1,

Note 16 (Fair Value Disclosure of Financial Instruments), and Note 17 (Financial Instruments with Off-Balance-Sheet Risk) of the 2004 Form 10-K. A description of the plans and the assumptions used to estimate the liabilities for pension and postretirement benefits is described in Note 12 (Benefit Plans) to the 2004 Form 10-K as well as Note 10 (Benefit Plans) in these consolidated financial statements.

4. Investment Securities — All investment securities of the Corporation are classified as available for sale. The available for sale classification provides the Corporation with more flexibility to respond, through the portfolio, to changes in market interest rates, or to increases in loan demand or deposit withdrawals.

     The Components of investment securities are as follows:

     Expected maturities will differ from contractual maturities based on the issuers’ rights to call or prepay obligations with or without call or prepayment penalties. Securities with remaining maturities over five years consist of mortgage and asset backed securities.

     The carrying amount of investment securities pledged to secure trust and public deposits and for purposes required or permitted by law amounted to approximately $2.1 billion at March 31, 2005, $1.9 billion at December 31, 2004, and $2.0 billion at March 31, 2004.

     At March 31, 2005 and 2004, Federal Reserve Bank (“FRB”) and Federal Home Loan Bank (“FHLB) stock amounted to $8.6 million, $104.0 million and $8.6 million, $99.7 million, respectively, and included in other securities in the preceding table. FRB and FHLB stock are classified as a restricted investment, carried at cost, and its value is determined by the ultimate recoverability of par value.

5. Allowance for loan losses (“ALL”) — The Corporation’s Credit Policy Division manages credit risk by establishing common credit policies for its subsidiary bank, participating in approval of their loans, conducting reviews of loan portfolios, providing centralized consumer underwriting, collections and loan operation services, and overseeing loan workouts. The Corporation’s objective is to minimize losses from its commercial lending activities and to maintain consumer losses at acceptable levels that are stable and consistent with growth and profitability objectives.

The activity within the ALL for the current and prior year first quarters, and the full year ended December 31, 2004 is shown in the following table:

     The $16.46 million overall decrease in the allowance for loan losses for the first quarter of 2005, compared to the first quarter of 2004, was primarily attributable to the additional provision taken in the first quarter of 2004. During the quarter ended March 31, 2004, the Corporation strengthened the allowance for loan losses by providing an additional $22.1 million above the quarter’s net charge-offs. During the first quarter 2004, Management observed that rising input costs such as plastic resins, steel and petroleum might impact certain segments of our commercial and industrial loan portfolio. Management also observed a higher level of nonaccrual loans from within the previously identified criticized loan levels. These observations led us to change some of the assumptions

utilized in the Corporation’s ALL methodology. Most notably, we shortened the historical period used for estimating loss migration factors, which had the effect of more heavily weighting recent loss history in the portfolio. Note 1 (Summary of Significant Accounting Policies) and Note 4 (Allowance for Loan Losses) in the 2004 Form 10-K more fully describe the components of the model.

6. Goodwill and Intangible Assets – The following table summarizes goodwill and intangible assets:

Amortizations expense for intangible assets was $0.22 million for both quarters ending March 31,2005 and 2004. The following table shows the estimated future amortization expense for deposit base intangible assets based on existing asset balances at December 31, 2004 for the yeas ended:

     During the first quarter of 2005, the Corporation conducted its annual impairment testing as required by SFAS No. 142 “Goodwill and Other Intangible Assets,” and concluded that goodwill was not impaired.

7. Earnings per share — The reconciliation between basic and diluted earnings per share (“EPS”) is presented as follows:

For the quarters ended March 31, 2005 and 2004, options to purchase 2.2 million and 1.9 million shares, respectively, were outstanding, but not included in the computation of diluted earnings per share because they were antidilutive.

8. Segment Information — The Corporation provides a diversified range of banking and certain nonbanking financial services and products through its various subsidiaries. Management reports the Corporation’s results through its major segment classification, Supercommunity Banking. Included in the Parent Company and Other Subsidiaries category are certain nonbanking affiliates and portions of certain assets, capital, and support functions not specifically identifiable with Supercommunity Banking.

     The Corporation’s business is conducted solely in the United States. The following tables present a summary of financial results as of and for the three-month periods ended March 31, 2005 and 2004 and the full year ended December 31, 2004:

9. Accounting for Derivatives — The Corporation follows the provisions of SFAS No. 133, “Accounting for Derivative Instruments and Hedging Activities” as amended by SFAS No. 149, in accounting for its derivative activities. At March 31, 2005, the Corporation had various interest rate swaps in place that were accounted for as fair value hedges under SFAS No. 133 since their purpose is to “swap” fixed interest rate liabilities and assets to a variable interest rate basis. All but one of the interest rate swaps are associated with the Corporation’s fixed-rate commercial loan swap program that was initiated during the first quarter of 2003 and the remaining interest rate swap converts the fixed interest rate of mandatorily redeemable trust preferred securities to a variable rate. All of these interest rate swaps, with the exception of the one associated with the mandatorily redeemable trust preferred securities, qualify for the “shortcut method of accounting” as prescribed in SFAS No. 133. The shortcut method of accounting requires that the hedge and the hedged item meet certain qualifying criteria. If the swap qualifies for the shortcut method of accounting then no hedge ineffectiveness can be assumed and the need to test for ongoing effectiveness is eliminated. For hedges that qualify for the shortcut method of accounting, the fair value of the swap and the fair value of the hedged item are recorded on the balance sheets and statements of income and comprehensive income. The remaining hedge does not meet all the criteria necessary to be considered for the shortcut method of accounting. Therefore, the long-haul method of accounting is utilized. The long-haul method of accounting requires periodic testing of hedge effectiveness with the portion of the hedge deemed to be ineffective reported in other operating expense.

     In the third quarter of 2004, the Corporation entered into forward swap agreements which, in effect, fixed the borrowing costs of certain variable rate liabilities in the future. These transactions did not qualify for the short-cut method of accounting under SFAS No. 133 as previously discussed. The Corporation classified these transactions as cash flow hedges, with any hedge ineffectiveness being reported in current earnings. It is anticipated that the hedge will prove to be highly effective. A correlation analysis performed at quarter-end proved that the hedge was effective.

     Additionally, in the normal course of business, the Corporation sells originated mortgage loans into the secondary mortgage loan markets. The Corporation maintains a risk management

program to protect and manage interest-rate risk and pricing associated with its mortgage commitment pipeline. The Corporation’s mortgage commitment pipeline included interest-rate lock commitments (“IRLCs”) that have been extended to borrowers who have applied for loan funding and met certain defined credit and underwriting standards. During the term of the IRLCs, the Corporation is exposed to interest-rate risk, in that the value of the IRLCs may change significantly before the loans close. To mitigate this interest-rate risk, the Corporation enters into various derivatives by selling loans forward to investors using forward commitments. In accordance with SFAS No. 133, the Corporation classifies and accounts for IRLCs as nondesignated derivatives that are recorded at fair value with changes in value recorded to current earnings. The forward sale commitments used to manage the risk on the IRLCs are also classified and accounted for as nondesignated derivatives and, therefore, recorded at fair value with changes recorded to current earnings. During 2003, the Corporation implemented a SFAS No. 133 hedging program for its mortgage loan warehouse to gain protection for the changes in fair value of the mortgage loan warehouse and the forward commitments. As such, both the mortgage loan warehouse the forward commitments are recorded at fair value with changes in value recorded to current earnings.

     In 2003, the Corporation began to enter into derivative contracts by purchasing To Be Announced Mortgage Backed Securities (“TBA Securities”) to help mitigate the interest-rate risk associated with its mortgage servicing rights (“MSR”). During the third quarter of 2004, options on treasury securities, options on mortgage-backed securities and swaptions were utilized to enhance the effectiveness of the economic hedge associated with the MSR. In Note 6 to the 2004 Form 10-K, the Corporation’s basis for accounting for mortgage servicing rights is discussed in more detail. In accordance with SFAS No. 133, the Corporation classifies and accounts for all three of these instruments as nondesignated derivatives. Accordingly, these securities are recorded at fair value with changes in value recorded to current earnings in loan sales and servicing income. At March 31, 2005, the Corporation did not have any TBA Securities, options, or swaptions outstanding.

10. Benefit Plans – The Corporation sponsors several qualified and nonqualified pension and other postretirement benefit plans for certain of its employees. The net periodic benefit cost is based on estimated values provided by outside actuaries. The components of net periodic benefit cost are as follows:

     The Corporation does not anticipate making a contribution to the pension plan during 2005.

     On December 8, 2003, President Bush signed the Modernization Act into law as disclosed in Note 2 of these consolidated financial statements. This law provides for a federal subsidy to sponsors of retiree health care benefit plans that provide a benefit that is at least actuarially equivalent to the benefit established by the Modernization Act. The federal subsidy in the Modernization Act resulted in a $1.6 million reduction in our accumulated postretirement benefit obligation. Concurrently during 2004, the Corporation amended its postretirement benefits plan to limit and cap benefits prospectively. The total impact of both changes on our actuarial liability was a decrease of $13.6 million and is being accounted for as an actuarial gain that will be amortized as a reduction of our periodic cost and liability.

     11. Contingencies — The nature of the Corporation’s business results in a certain amount of litigation. Accordingly, FirstMerit Corporation and its subsidiaries are subject to various pending and threatened lawsuits in which claims for monetary damages are asserted. Management, after consultation with legal counsel, is of the opinion that the ultimate liability of such pending matters would not have a material effect on the Corporation’s financial condition and results of operations.

ITEM 2. MANAGEMENT’S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS

AVERAGE CONSOLIDATED BALANCE SHEETS (Unaudited)
Fully-tax Equivalent Interest Rates and Interest Differential