FORM 11-K SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 (Mark One) [X] ANNUAL REPORT PURSUANT TO SECTION 15 (d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31, 2004 OR [ ] TRANSITION REPORT PURSUANT TO SECTION 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from __________ to __________ Commission file number: 1-13923 WAUSAU PAPER CORP. SAVINGS AND INVESTMENT PLAN (Full title of the plan and the address of the plan, if different from the issuer named below) WAUSAU-MOSINEE PAPER CORPORATION SAVINGS AND INVESTMENT PLAN (Former name or former address, if changed from last report) WAUSAU PAPER CORP. 100 PAPER PLACE MOSINEE, WI 54455-9099 (Name of issuer of the securities held pursuant to the plan and the address of its principal executive office) WAUSAU-MOSINEE PAPER CORPORATION 1244 KRONENWETTER DRIVE MOSINEE, WI 54455-9099 (Former name or former address, if changed from last report) WAUSAU-MOSINEE PAPER CORPORATION SAVINGS AND INVESTMENT PLAN TABLE OF CONTENTS PAGE REPORT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM 1 FINANCIAL STATEMENTS: Statements of Net Assets Available for Benefits for the Years Ended December 31, 2004 and 2003 2 Statements of Changes in Net Assets Available for Benefits for the Years Ended December 31, 2004 and 2003 3 Notes to Financial Statements 4-9 SUPPLEMENTAL SCHEDULE - Form 5500, Schedule H, Part IV, Line 4i - Schedule of Assets (Held at End of Year) December 31, 2004 10 Schedules not filed herewith are omitted because of the absence of conditions under which they are required. -i- REPORT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM To the Wausau-Mosinee Paper Corporation Savings and Investment Plan Mosinee, Wisconsin: We have audited the accompanying statements of net assets available for benefits of Wausau-Mosinee Paper Corporation Savings and Investment Plan (the "Plan") as of December 31, 2004 and 2003, and the related statements of changes in net assets available for benefits for the years then ended. These financial statements are the responsibility of the Plan's management. Our responsibility is to express an opinion on these financial statements based on our audits. We conducted our audits in accordance with the standards of the Public Company Accounting Oversight Board (United States). Those standards require that we plan and perform the audit to obtain reasonable assurance about whether the financial statements are free of material misstatement. The Plan is not required to have, nor were we engaged to perform, an audit of its internal control over financial reporting. Our audits included consideration of internal control over financial reporting as a basis for designing audit procedures that are appropriate in the circumstances, but not for the purpose of expressing an opinion on the effectiveness of the Company's internal control over financial reporting. Accordingly, we express no such opinion. An audit also includes examining, on a test basis, evidence supporting the amounts and disclosures in the financial statements, assessing the accounting principles used and significant estimates made by management, as well as evaluating the overall financial statement presentation. We believe that our audits provide a reasonable basis for our opinion. In our opinion, such financial statements present fairly, in all material respects, the net assets available for benefits of the Plan as of December 31, 2004 and 2003, and the changes in net assets available for benefits for the years then ended in conformity with accounting principles generally accepted in the United States of America. Our audits were conducted for the purpose of forming an opinion on the basic financial statements taken as a whole. The supplemental schedule listed in the Table of Contents is presented for the purpose of additional analysis and is not a required part of the basic financial statements, but is supplementary information required by the Department of Labor's Rules and Regulations for Reporting and Disclosure under the Employee Retirement Income Security Act of 1974. This schedule is the responsibility of the Plan's management. Such schedule has been subjected to the auditing procedures applied in our audit of the basic financial statements and, in our opinion, is fairly stated in all material respects when considered in relation to the basic financial statements taken as a whole. DELOITTE & TOUCHE LLP Milwaukee, Wisconsin June 13, 2005 -1- WAUSAU-MOSINEE PAPER CORPORATION SAVINGS AND INVESTMENT PLAN STATEMENTS OF NET ASSETS AVAILABLE FOR BENEFITS DECEMBER 31, 2004 AND 2003 2004 2003 ASSETS: Cash and cash equivalents $ 386 $ 177,634 Investments 184,272,282 168,908,662 Receivables: Employer 41,283 92,899 Participants 149,693 180,512 Accrued income 143,116 137,169 Other receivables 52,066 57,908 Total receivables 386,158 468,488 NET ASSETS AVAILABLE FOR BENEFITS $184,658,826 $169,554,784 See notes to financial statements. -2- WAUSAU-MOSINEE PAPER CORPORATION SAVINGS AND INVESTMENT PLAN STATEMENTS OF CHANGES IN NET ASSETS AVAILABLE FOR BENEFITS YEARS ENDED DECEMBER 31, 2004 AND 2003 2004 2003 ADDITIONS: Net appreciation in fair value of investments $12,450,482 $25,884,612 Contributions: Employer 2,680,369 2,622,928 Participants 10,151,551 9,987,650 Participant rollovers 257,604 135,796 Total contributions 13,089,524 12,746,374 Interest income 1,764,251 1,893,960 Dividend income 532,798 363,554 Total additions 27,837,055 40,888,500 DEDUCTIONS: Benefits paid to participants 12,644,529 6,394,359 Administrative expenses 88,484 94,837 Total deductions 12,733,013 6,489,196 NET INCREASE 15,104,042 34,399,304 NET ASSETS AVAILABLE FOR BENEFITS: Beginning of year 169,554,784 135,155,480 End of year $184,658,826 $169,554,784 See notes to financial statements. -3- WAUSAU-MOSINEE PAPER CORPORATION SAVINGS AND INVESTMENT PLAN NOTES TO FINANCIAL STATEMENTS YEARS ENDED DECEMBER 31, 2004 AND 2003 1. PLAN DESCRIPTION The following brief description of the Wausau-Mosinee Paper Corporation Savings and Investment Plan (the "Plan") is provided for general information purposes only. The Plan is subject to certain provisions of the Employee Retirement Income Security Act of 1974 ("ERISA") and Section 401 of the Internal Revenue Code ("IRC"). Participants should refer to the Plan document for more complete information. An employee initially becomes eligible to participate at times varying from one day of service to 120 days of service, depending upon the employee's classification and his or her employment date. GENERAL-The Plan was established on January 1, 1988. It is a defined contribution plan that covers all full-time salaried, non-union hourly and all collectively bargained common law employees of Wausau-Mosinee Paper Corporation and its subsidiaries (the "Company"). CONTRIBUTIONS-Participants are allowed to contribute up to 16% of their gross annual compensation, as defined in the Plan document, subject to certain statutory limitations. The Plan allows participants to rollover distributions from another employer's retirement plan or an annuity contract as contributions, subject to certain restrictions. Participants may deposit any portion of a distribution that has not been taxed, provided the deposit is eligible for rollover under the IRC. These deposits are not subject to the contribution limitations under the IRC. The Company does not match these contributions. NON-BARGAINED EMPLOYEES-The Company currently matches non-bargained participant contributions at a rate of $0.50 for every $1.00 contributed on the first 3% and $.35 for every $1.00 contributed on the second 3%, up to 6% of a participant's annual compensation as defined in the Plan. The Plan allows the Board of Directors to determine a discretionary matching contribution to be made for participants employed on the last day of the year or who terminated employment during the year due to death, retirement on or after attainment of age 55, or disability. There were no discretionary matching contributions for the years ended December 31, 2004 and 2003. -4- BARGAINED EMPLOYEES-The Company matching contribution differs by collective bargaining unit. Bargained employees of certain collective bargaining units do not receive a matching contribution while other employees receive a matching contribution. The maximum matching contribution of any collective bargaining unit was $2.03 per $1.00 contributed up to 3% of a participant's annual gross compensation. PARTICIPANT ACCOUNTS-Individual accounts are maintained for each of the Plan's participants to reflect the participant's contributions and related employer contributions, as well as the participant's share of the Plan's income and any related administrative expenses. Allocations are based on the proportion that each participant's account balance has to the total of all participants' account balances. INVESTMENT OPTIONS-The Plan allows participants to direct the investment of all contributions and related earnings among various mutual funds, various pooled equity and fixed income funds and a Company common stock fund consisting of common stock of the Company and short-term, interest bearing instruments. ALLOCATION OF INVESTMENT INCOME (LOSS)-Each participant's account is allocated investment income (loss) based upon the specific investment options chosen and in the proportion that an individual participant's account balance bears in relation to total account balances under the Plan. VESTING-Participants are fully vested in their salary deferral and rollover contributions plus earnings/losses thereon. Vesting in the Company's matching contributions plus actual earnings/losses thereon is based on years of service and the participant's employment status as either non- bargained or bargained. Non-bargained participants are fully vested in the Company's contributions after three years of vesting service, or at the rate of 33 1/3% per year of service. Bargained participants vest in the Company's matching contributions according to varying vesting schedules depending on the terms of the applicable collective bargaining agreement. A year of vesting consists of a calendar year in which an employee works a minimum of 1,000 hours for the Company. Participant contributions and earnings thereon, rollover contributions, and vested Company contributions and earnings thereon may be withdrawn for any reason after a participant reaches age 59 1/2 or at any age if a participant demonstrates financial hardship. Financial hardship withdrawals are subject to government regulation and may be subject to a 10% penalty. PAYMENT OF BENEFITS-On termination of service due to death, disability, or retirement, the vested portion of a participant's account is payable to the participant, or a named beneficiary, based on the participant's elected payment method. The payment options available are lump-sum or periodic payments. A nontransferable annuity optional form of benefit was available prior to October 1, 2002. -5- FORFEITURES-Plan forfeitures arise as a result of participants who terminate service with the Company before becoming fully vested in the Company's contribution. These forfeitures are used to reduce future Company contributions. Certain forfeitures relating to the Mosinee Thrift Plan prior to January 1, 1999 are allocated to certain participant accounts in accordance with the Plan document. The amount of forfeitures available at December 31, 2004 and 2003 was $444,868 and $369,456, respectively. PARTICIPANT LOANS-Participants may borrow from their accounts. Loan transactions are treated as a segregated investment of the participant's accounts. Loan terms range from one to five years or longer if for the purchase of a primary residence. Loans may not exceed the lesser of 50% of the participant's account balance or $50,000, and are secured by the balance in the participant's account. The loans bear interest at a rate commensurate with local prevailing rates as determined from time to time by the Company's employee benefits committee. Interest rates on existing loans range from 4.00% to 10.50%. Principal and interest are paid ratably through payroll deductions. Upon termination of employment, outstanding balances become due and payable to the Plan, unless the borrower elects to continue making repayments in accordance with the promissory note evidencing the loan. PLAN EXPENSES-Administrative expenses charged by the third party administrator and all other expenses incurred in conjunction with the Plan are paid by the Company. Investment advisory and management fees are allocated proportionately to Plan participants based on their respective account balances. Loan fees are charged directly to the participant's account against the investment option for which the loan was originally charged. PLAN TERMINATION-Although it has not expressed any intent to do so, Wausau- Mosinee Paper Corporation has the right under the Plan to terminate the Plan subject to the provisions of ERISA. Upon termination of the Plan, all account balances of the participants become fully vested. The account will be held under the Plan and continue to accrue investment earnings until all vested benefits have been distributed according to the terms of the Plan. 2. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES BASIS OF PRESENTATION-The accompanying financial statements have been prepared on the accrual basis of accounting in accordance with accounting principles generally accepted in the United States. BENEFITS-Benefits are recorded when distributed. The amount of benefit payments requested in 2004 that were distributed in 2005 was $220,646. The amount of benefit payments requested in 2003 that were distributed in 2004 was $398,428. INVESTMENT VALUATION AND INCOME RECOGNITION-The Plan's various mutual fund and company stock investments are carried at fair value which represents the quoted market values of the underlying investments on the last business day of the plan year including -6- current income and investment expenses. Investments in the M&I Stable Principal Fund are stated at contract value which approximates fair value. Loans are stated at estimated fair value and are deemed collectible. Securities transactions are accounted for on the trade-date basis (the date the order to buy or sell is executed). Gains or losses on security transactions are recorded as the difference between proceeds received and the carrying value of the investments. Interest income is recognized on the accrual method, and dividend income is recorded on the ex-dividend date. Net appreciation and depreciation in fair value of investments on the statements of changes in net assets available for benefits includes both unrealized appreciation or depreciation and realized gains and losses. Interest and dividends are identified separately. USE OF ESTIMATES-The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America requires Plan management to make estimates and assumptions that affect the reported amounts of net assets available for benefits and changes therein. Actual results could differ from those estimates. The Plan utilizes various investment instruments, including mutual funds and investment contracts. Investment securities are exposed to various risks including but not limited to, interest rate, market, and credit risks. Due to the level of risk associated with certain investment securities, it is reasonably possible that changes in the value of investment securities will occur in the near term. 3. INVESTMENTS The following represents a summary of the fair value of investments at December 31, 2004 and 2003. Investments that individually represent 5% or more of the Plan's net assets available for benefits are separately identified. -7- ASSET FAIR VALUE 2004 2003 INVESTMENTS AT FAIR VALUE AS DETERMINED BY QUOTED MARKET PRICE Common/collective trust: Northern Capital Management Fund, 2,676,430 and 2,935,084 shares, respectively $30,247,155 $32,122,882 Employer Common Stock* 6,815,792 6,798,430 Pooled separate accounts 6,938,772 5,895,261 Registered investment companies: ABN AMRO Growth Fund, 527,523 and 566,640 shares, respectively 12,206,891 12,449,076 Brandywine Blue Chip Fund, 471,776 and 482,722 shares, respectively 13,403,154 11,498,429 Thompson Plumb Growth Fund, 296,875 and 281,897 shares, respectively 13,890,762 12,936,266 Vanguard 500 Index Fund, 111,245 and 103,701 shares, respectively 12,419,415 10,648,008 Artisan International Fund, 458,127 and 425,783 shares, respectively 10,142,926 8,051,563 Royce Opportunity Fund, 728,223 and 531,916 shares, respectively 9,590,695 6,409,586 Other 23,022,157 18,831,735 Total registered investment companies 94,676,000 80,824,663 INVESTMENTS AT ESTIMATED VALUE Participant loans* 2,921,610 2,616,778 INVESTMENTS AT CONTRACT VALUE Investment contracts between financial institutions - M&I Stable Principal Fund,* 42,672,953 and 40,650,648 shares, respectively 42,672,953 40,650,648 TOTAL INVESTMENTS $184,272,282 $168,908,662*Party-in-interest -8- During 2004 and 2003, the Plan's investments (including investments bought, sold, and held during the year) appreciated in value as follows: NET CHANGE IN FAIR VALUE 2004 2003 INVESTMENTS AT FAIR VALUE DETERMINED BY QUOTED MARKET PRICE: Common/collective trusts $ 980,221 $ 6,073,399 Employer Common Stock 1,789,982 1,387,520 Pooled separate accounts/investment contract 572,874 1,029,551 Registered investment companies 9,107,405 17,394,142 $12,450,482 $25,884,612 4. INVESTMENT CONTRACT In 2004 and 2003, the Plan maintained an investment contract with Marshall & Ilsley Trust Company ("M&I"). Contributions are maintained in a pooled account. The account is credited with earnings on the underlying investments and charged for Plan withdrawals and administrative expenses charged by M&I. The contract is included in the financial statements at contract value, which approximates fair value, as reported to the Plan by M&I. Contract value represents contributions made under the contract plus earnings, less plan withdrawals and administrative expenses. The average yield and crediting interest rates on the contract were 4.01% and 3.91%, respectively, for the year ended December 31, 2004 and 4.33% and 4.11% for the year ended December 31, 2003, respectively. The basis and frequency of determining the crediting interest rate is done on a daily basis. There were no guarantees or limitations on the contract at December 31, 2004 and 2003. 5. FEDERAL INCOME TAX STATUS The Internal Revenue Service has determined and informed the Company by a letter dated July 18, 2003, that the Plan is qualified and the trust established under the Plan is tax-exempt, under the appropriate sections of the IRC. 6. RELATED PARTY TRANSACTIONS The Plan invests in Company common stock. In addition, certain plan investments represent shares of mutual funds and collective trust funds managed by the Trustee. These transactions are considered party-in-interest transactions. These transactions are not, however, considered prohibited transactions under ERISA regulations. Fees paid by the Plan for investment management services were included as a reduction of the return earned on each fund. -9- WAUSAU-MOSINEE PAPER CORPORATION SAVINGS & INVESTMENT PLAN FORM 5500, SCHEDULE H, PART IV, LINE 4I - SCHEDULE OF ASSETS (HELD AT END OF YEAR) DECEMBER 31, 2004 DESCRIPTION OF INVESTMENT INCLUDING MATURITY DATE, NUMBER IDENTITY OF ISSUE, BORROWER, RATE OF INTEREST, COLLATERAL, OF SHARES/ FAIR LESSOR OR SIMILAR PARTY PAR OR MATURITY VALUE PAR VALUE VALUE Marshall & Ilsley Trust Company* Common/collective trust - Northern Capital Management Fund 2,676,430 $30,247,155 Marshall & Ilsley Trust Company* Employer Common Stock - Wausau-Mosinee Common Stock Fund 372,040 6,815,792 Marshall & Ilsley Trust Company* Pooled separate account - M&I Aggressive Balanced Portfolio Fund 61,280 1,618,379 Marshall & Ilsley Trust Company* Pooled separate account - M&I Moderate Balanced Portfolio Fund 132,696 2,958,922 Marshall & Ilsley Trust Company* Pooled separate account - M&I Diversified Stock Portfolio Fund 83,043 2,361,471 Marshall & Ilsley Trust Company* Pooled separate account - M&I Stable Principal Fund 42,672,953 42,672,953 AIM Small Cap Growth Fund Registered investment company - AIM Small Cap Growth Fund 35,059 962,721 Artisan International Fund Registered investment company - Artisan International Fund 458,127 10,142,926 Brandywine Blue Chip Fund Registered investment company - Bradywine Blue Chip Fund 471,776 13,403,154 ABN AMRO Growth Fund Registered investment company - ABN AMRO Growth Fund 527,523 12,206,891 Fidelity Advisor Equity Income Fund Registered investment company - Fidelity Advisor Equity Income Fund 156,217 4,425,629 MFS Mid Cap Growth Fund Registered investment company - MFS Mid Cap Growth Fund 803,367 7,182,098 Marshall Mid Cap Value Fund* Registered investment company - Marshall Mid Cap Value Fund 327,394 4,930,552 Royce Opportunity Fund Registered investment company - Royce Opportunity Fund 728,223 9,590,695 Dreyfus Premier Balanced Opp Fund Registered investment company - Dreyfus Premier Balanced Opp Fund 281,836 5,521,157 Thompson Plumb Growth Fund Registered investment company - Thompson Plumb Growth Fund 296,875 13,890,762 Vanguard 500 Index Fund Registered investment company - Vanguard 500 Index Fund 111,245 12,419,415 Participant Loans* Rate during year 4.0% - 10.5% 2,921,610 2,921,610 Total assets (held at end of year) $184,272,282 * Party-in-interest. -10- SIGNATURES Pursuant to the requirements of the Securities Exchange Act of 1934, the Plan administrator of the Wausau-Mosinee Paper Corporation Savings and Investment Plan has duly caused this annual report to be signed on its behalf by the undersigned hereunto duly authorized. WAUSAU-MOSINEE PAPER CORPORATION EMPLOYEE BENEFITS COMMITTEE DATE: June 29, 2005 By: STUART R. CARLSON Stuart R. Carlson Chairman -11- EXHIBIT INDEX TO FORM 11-K OF WAUSAU-MOSINEE PAPER CORPORATION SAVINGS AND INVESTMENT PLAN FOR THE YEAR ENDED DECEMBER 31, 2004 Pursuant to Section 102(d) of Regulation S-T (17 C.F.R. Section 232.102(d)) Exhibit 23.1 Consent of Deloitte & Touche LLP -12-