UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 11-K [X] ANNUAL REPORT PURSUANT TO SECTION 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31, 2003 or [ ] TRANSITION REPORT PURSUANT TO SECTION 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from __________ to ___________ Commission File Number: 1-9894 A. Full title of the plan and address of the plan, if different from that of the issuer named below: ALLIANT ENERGY CORPORATION 401(k) SAVINGS PLAN B. Name of issuer of the securities held pursuant to the plan and the address of its principal executive office: ALLIANT ENERGY CORPORATION 4902 North Biltmore Lane Madison, Wisconsin 53718 REQUIRED INFORMATION The following financial statements and schedules of the Alliant Energy Corporation 401(k) Savings Plan, prepared in accordance with the financial reporting requirements of the Employee Retirement Income Security Act of 1974, as amended, are filed herewith. Page 1 of 19 pages Exhibit Index is on page 18 1 ALLIANT ENERGY CORPORATION 401(k) SAVINGS PLAN FINANCIAL STATEMENTS AS OF DECEMBER 31, 2003 AND 2002 AND FOR THE YEAR ENDED DECEMBER 31, 2003, SUPPLEMENTAL SCHEDULES FOR THE YEAR ENDED DECEMBER 31, 2003, AND REPORT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM 2 ALLIANT ENERGY CORPORATION 401(k) SAVINGS PLAN TABLE OF CONTENTS Page No. REPORT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM 4 FINANCIAL STATEMENTS Statements of Net Assets Available for Plan Benefits as of December 31, 2003 and 2002 5 Statement of Changes in Net Assets Available for Plan Benefits for the Year Ended December 31, 2003 6 NOTES TO FINANCIAL STATEMENTS 7-13 SUPPLEMENTAL SCHEDULES Form 5500, Schedule H, Part IV, line 4i - Schedule of Assets (Held at End of Year) as of December 31, 2003 14-15 Form 5500, Schedule H, Part IV, line 4j - Schedule of Reportable Transactions for the Year Ended December 31, 2003 16 SIGNATURES 17 EXHIBIT INDEX 18 Independent Registered Public Accounting Firm Consent 19 3 Report of Independent Registered Public Accounting Firm To the Plan Administrator of the Alliant Energy Corporation 401(k) Savings Plan: We have audited the accompanying statements of net assets available for plan benefits of the Alliant Energy Corporation 401(k) Savings Plan (the "Plan") as of December 31, 2003 and 2002, and the related statement of changes in net assets available for plan benefits for the year ended December 31, 2003. 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. An audit includes examining, on a test basis, evidence supporting the amounts and disclosures in the financial statements. An audit also includes 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 plan benefits of the Plan as of December 31, 2003 and 2002, and the changes in net assets available for plan benefits for the year ended December 31, 2003, 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 schedules listed in the Table of Contents are presented for the purpose of additional analysis and are not a required part of the basic financial statements, but are 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. These schedules are the responsibility of the Plan's management. Such schedules have been subjected to the auditing procedures applied in our audit of the basic 2003 financial statements and, in our opinion, are fairly stated in all material respects when considered in relation to the basic financial statements taken as a whole. /s/ Deloitte & Touche LLP Milwaukee, Wisconsin June 14, 2004 4 ALLIANT ENERGY CORPORATION 401(k) SAVINGS PLAN STATEMENTS OF NET ASSETS AVAILABLE FOR PLAN BENEFITS December 31, 2003 2002 --------------------- -------------------- Investment income receivable $6,819,703 $5,310,516 Contributions receivable 424,518 - --------------------- -------------------- Total receivables 7,244,221 5,310,516 --------------------- -------------------- Investments, other than participant promissory notes (Refer to Note 7) 385,431,715 281,098,340 Participant promissory notes 8,213,703 7,663,518 --------------------- -------------------- Total investments 393,645,418 288,761,858 --------------------- -------------------- Net assets available for plan benefits $400,889,639 $294,072,374 ===================== ==================== The accompanying Notes to Financial Statements are an integral part of these statements. 5 ALLIANT ENERGY CORPORATION 401(k) SAVINGS PLAN STATEMENT OF CHANGES IN NET ASSETS AVAILABLE FOR PLAN BENEFITS For the Year Ended December 31, 2003 Net assets available for plan benefits - beginning of year $294,072,374 Contributions: Cash contributions from employees 22,933,813 Rollovers from other qualified plans 330,882 Employer contributions: Cash 719,074 Cash for purchase of Alliant Energy Corporation common stock 6,936,742 Investment activity: Investment income 7,660,523 Net appreciation in fair value of investments (Refer to Note 7) 79,787,999 Distributions: Distributions to participants (11,551,768) ------------------- Net assets available for plan benefits - end of year $400,889,639 =================== The accompanying Notes to Financial Statements are an integral part of this statement. 6 ALLIANT ENERGY CORPORATION 401(k) SAVINGS PLAN NOTES TO FINANCIAL STATEMENTS FOR THE YEAR ENDED DECEMBER 31, 2003 Note 1. Description of the Plan The Alliant Energy Corporation 401(k) Savings Plan (the Plan) is a qualified defined contribution plan under Section 401(k) of the Internal Revenue Code (the Code), as amended, and meets the applicable requirements of the Employee Retirement Income Security Act of 1974, as amended. The following brief description of the Plan is provided for general information purposes only. More complete information regarding the Plan is provided in the summary plan description, which has been made available to all eligible Plan participants. The Plan is administered by the Employee Total Compensation Committee (the Committee) and the Plan sponsor is Alliant Energy Corporate Services, Inc. (a direct subsidiary of Alliant Energy Corporation), which reserves the right to terminate, amend or modify the Plan if future conditions warrant such action. Any regular employee of Alliant Energy Corporation and its participating subsidiaries (the Company) age 18 and over may become a participant in the Plan. Regular full-time employees and regular part-time employees customarily scheduled to work at least half-time may participate immediately following 30 days of service. Part-time employees customarily scheduled to work less than half-time may participate after 12 months of service during which he or she has earned at least 1,000 paid hours. Wisconsin Power and Light Company "special temporary" bargaining unit employees are also eligible under the same rules as "regular" employees. Effective Jan. 1, 2002, the Company adopted an Employee Stock Ownership Plan (ESOP) within the Plan. Under the new provisions, Plan participants have the option to elect to receive cash for any dividends paid on Company common stock within the Plan or to have the dividends reinvested in additional shares based on the current market price. Also, the Company is eligible for the dividend deduction provisions of Section 404(k) of the Code for common stock held in the ESOP. The Company provides guaranteed matching contributions for each $1 contributed by participants up to a maximum of the first 6% of the participants' compensation. Other than the exceptions noted below, Company match information and employee contribution limits for 2003 were as follows: Company match for each $1 contributed up to the maximum $0.50 Eligible employee annual contribution limit as a percentage of compensation: Jan. 1 - March 31 19% April 1 - Dec. 31 50% Maximum annual contribution limit $12,000 Beginning with the 2003 Plan year, participants who were at least 50 years old by Dec. 31, 2003 were eligible to make catch-up contributions of up to $2,000 in 2003. These catch-up contributions were not eligible for any Company match. The contributions for Alliant Energy Resources, Inc. (Resources) and Cedar Rapids and Iowa City Railway Company (CRANDIC) employees are calculated based on a percentage of base pay, without overtime or incentive pay, and there is a "basic" Company contribution equal to 4% and 2%, respectively, of base pay. 7 Company contributions for Resources and CRANDIC employees are invested at the participants' discretion. All other matching contributions by the Company are invested in the Alliant Energy Corporation Common Stock Fund. Resources and CRANDIC employees may be eligible for a discretionary Company contribution of $0.50 for every $1 contributed up to a maximum of the first 6% of pay in addition to the "basic" Company contribution. The discretionary contribution for both Resources and CRANDIC employees is based on goals established by Resources and is typically determined and paid during the first quarter of the following year. The discretionary Company contributions for 2003 and 2002 were $424,518 and $0, respectively. An additional Company contribution is allocated to the accounts of active Plan participants, except for Resources and CRANDIC employees, as of the last day of the Plan year, who had contributed 6% of compensation during the Plan year and did not receive a Company matching contribution equal to 3% of compensation. The amount of the additional Company contribution is the difference between 3% of compensation during the Plan year and the amount of Company matching contributions previously received during the Plan year. Participants are immediately vested in their employee and employer contributions. Contributions under the Plan are held and invested, until distribution, in a Trust Fund maintained by American Express Trust Company (the Trustee), a division of American Express Financial Advisors Inc. The investment options available to participants at Dec. 31, 2003 were Stable Capital Fund, PIMCO Total Return Fund, American Express Trust Short-Term Horizon (25:75) Fund, American Express Trust Long-Term Horizon (65:35) Fund, Dodge & Cox Stock Fund, American Express Trust Long-Term Horizon (80:20) Fund, American Express Trust Equity Index Fund III, Evergreen Small Cap Value Fund, Vanguard Mid-Cap Index Fund, EuroPacific Growth Fund, The Growth Fund of America, The Brown Capital Management Small Company Fund, Dreyfus Premier Emerging Markets Fund, American Express Trust Bond Index Fund II, Self-Managed Brokerage Account, Alliant Energy Corporation Company Stock Fund, or a combination of the sixteen funds. The investment options available to participants at Dec. 31, 2002 were Stable Capital Fund, PIMCO Total Return Fund, American Express Trust Short-Term Horizon (25:75) Fund, American Express Trust Long-Term Horizon (65:35) Fund, Dodge & Cox Stock Fund, American Express Trust Long-Term Horizon (80:20) Fund, American Express Trust Equity Index Fund III, Undiscovered Managers Small Cap Value Fund, Vanguard Mid-Cap Index Fund, Putnam International Growth Fund, The Growth Fund of America, The Brown Capital Management Small Company Fund, Alliant Energy Corporation Company Stock Fund, or a combination of the thirteen funds. Additionally, participants may subsequently redesignate the distribution of future contributions or transfer existing balances between investment funds on a daily basis, subject to the limits set forth in the Plan. Company matching contributions invested in the Alliant Energy Corporation Company Stock Fund may not be transferred to any other investment fund, except for contributions made for CRANDIC and Resources employees as previously described; however, Company matching contributions may be transferred by certain participants during the 30-day period immediately prior to retirement and beginning with the 2003 Plan year, participants age 55 with 10 years of service were eligible to diversify up to 100% of their ESOP account to one or more of the investment options. A brief description of the investment options at Dec. 31, 2003 is as follows: Stable Capital Fund. The Stable Capital Fund is a stable value fund. Its objective is to preserve principal while seeking a competitive level of current income. The Stable Capital Fund is intended to be a lower risk investment with a higher return than is typically offered by money market funds, while it maintains liquidity and safety of principal. The fund is invested primarily in Guaranteed Investment Contracts (GIC's) issued by one or more insurance companies or other financial institutions. The fund may also invest in the American Express Trust Income Fund I and the American Express Trust Money Market Fund I. The carrying value of all GIC investments was $38,189,962 and $36,564,953 at Dec. 31, 2003 and 2002, respectively. The approximate fair value of these investments was $46,026,501 and $43,781,042 at Dec. 31, 2003 and 2002, respectively, based on the discounted cash flows valuation method. Under the terms of the GIC's, the weighted average crediting interest rate was 4.08% and 5.62% on Dec. 31, 2003 and 2002, respectively, and is reset quarterly for all contracts. The GIC's earned an average rate of 5.67% in 2003. 8 PIMCO Total Return Fund. The PIMCO Total Return Fund is an actively managed, intermediate maturity bond portfolio. Its objective is to maximize total return, consistent with preservation of capital and prudent investment management, in order to exceed the returns of the bond market as a whole as represented by the Lehman Brothers Aggregate Bond Index. It invests in a portfolio of intermediate maturity bonds, typically with a majority in treasury and mortgage-backed bonds. The average duration ranges between 3 and 6 years. American Express Trust Short-Term Horizon (25:75) Fund. The American Express Trust Short-Term Horizon (25:75) Fund is a lifestyle fund. Its objective is to seek to create a diversified portfolio with a conservative risk profile appropriate for individuals with short-term time horizons. It invests in a predetermined mix of growth, growth/income, income and money market (cash equivalent) investment funds. American Express Trust Long-Term Horizon (65:35) Fund. The American Express Trust Long-Term Horizon (65:35) Fund is a lifestyle fund. Its objective is to seek to create a diversified portfolio with a conservative risk profile appropriate for individuals with long-term time horizons. It invests in a predetermined mix of growth, growth/income and income investment funds. Dodge & Cox Stock Fund. The Dodge & Cox Stock Fund is a large cap value fund. Its primary objective is to seek long-term growth of principal and income and secondary objective is to achieve a reasonable current income. It invests primarily in a broadly diversified and carefully selected portfolio of common stock. The fund typically invests at least 80% of its total assets in common stock. American Express Trust Long-Term Horizon (80:20) Fund. The American Express Trust Long-Term Horizon (80:20) Fund is a lifestyle fund. Its objective is to seek to create a diversified portfolio with a moderate risk profile appropriate for individuals with long-term time horizons. It invests in a predetermined mix of growth, growth/income and income investment funds. American Express Trust Equity Index Fund III. The American Express Trust Equity Index Fund III is a growth and income fund. Its objective is to provide investment results that correspond to the price and yield performance of publicly traded stocks, in aggregate, as represented by the Standard & Poor's 500 Composite Stock Price Index (S&P 500). It invests in a portfolio consisting primarily of common stocks of the S&P 500. Evergreen Small Cap Value Fund. The Evergreen Small Cap Value Fund, formerly known as the Undiscovered Managers Small Cap Value Fund, is a small cap value fund. Its objective is to seek long-term growth of capital by primarily investing in common stocks of companies with smaller market capitalizations. Vanguard Mid-Cap Index Fund. The Vanguard Mid-Cap Index Fund is a mid cap/core fund. Its objective is to seek long-term capital growth by tracking the performance of the Standard & Poor's MidCap 400 Index, which comprises a market-weighted growth of medium-sized United States of America (U.S.) companies. It invests in these medium-sized U.S. companies. EuroPacific Growth Fund. Effective Dec. 31, 2003, the EuroPacific Growth Fund replaced the Putnam International Growth Fund. Participants who had monies invested in the Putnam International Growth Fund had their current and future contributions transferred to the EuroPacific Growth Fund. The EuroPacific Growth Fund is a foreign stock fund. It seeks long-term growth of capital by investing primarily in stocks of issuers located in Europe and the Pacific Basin. The Growth Fund of America. The Growth Fund of America is a large cap growth fund. It seeks to achieve long-term growth of capital. It invests primarily in common stocks of companies that appear to offer superior opportunities for growth of capital. 9 The Brown Capital Management Small Company Fund. The Brown Capital Management Small Company Fund is a small cap growth fund. It seeks capital appreciation by investing primarily in equities issued by companies with total operating revenues of $250 million or less. Dreyfus Premier Emerging Markets Fund. The Dreyfus Premier Emerging Markets Fund is a growth fund. Its objective is to achieve long-term capital appreciation by investing at least 80% of its assets in the stocks of companies organized, or with a majority of assets or business, in emerging market countries. American Express Trust Bond Index Fund II. The American Express Trust Bond Index Fund II is an income fund. Its objective is to approximate as closely as possible the total return of the Lehman Brothers Aggregate Bond Index, an unmanaged index. It invests in the Pyramid Broad Market Fixed Income Index Fund which invests primarily in high-quality corporate bonds and U.S. government securities. Self-Managed Brokerage Account. The Self-Managed Brokerage Account allows participants to invest in a wide range of mutual funds outside of the core investment options available in the Plan. At Dec. 31, 2003, the Self-Managed Brokerage Account consisted of the Primary Reserve Fund. Alliant Energy Corporation Company Stock Fund. This fund is invested primarily in common stock of the Company. A portion of the fund (1-2% of total fund assets) may also be invested in the American Express Trust Money Market Fund I to help provide liquidity for transfers out of the fund. Purchases and sales of common stock are made by the Trustee on the open market. Under the ESOP, Plan participants have the option to elect to receive cash for any dividends paid on Company common stock within this fund or to have the dividends reinvested in additional shares based on the current market price. Participant Loans. The Plan has provisions under which participants may take loans up to the lesser of $50,000 or 50% of their total account balance (a $1,000 minimum loan amount and a maximum of three loans for each participant also apply). The Committee determines the loan interest rate pursuant to the Plan. Interest rates on participant loans ranged from 5.0% to 10.5% at Dec. 31, 2003 and 5.25% to 10.5% at Dec. 31, 2002. Note 2. Summary of Significant Accounting Policies (a) Basis of Accounting - The financial statements have been prepared in accordance with accounting principles generally accepted in the U.S. (b) Valuation of Investments and Income Recognition - All GIC's held by the Plan are fully benefit responsive and are valued at contract value, which represents contributions made under the contract, plus interest at the contract rate (less funds used to pay plan benefits). Participant loans are carried at unpaid principal balances due. All other Plan investments are carried at fair value as determined by quoted market prices. Interest income is accrued when earned. Dividend income is recorded on the ex-dividend date. Investment transactions are recorded on the trade date. (c) Net Appreciation in Fair Value of Investments - Net realized and unrealized appreciation is recorded in the accompanying statement of changes in net assets available for plan benefits as "Net appreciation in fair value of investments." (d) Payment of Benefits - Benefit payments to participants are recorded when paid. (e) Expenses - Investment management fees are paid from investment earnings prior to crediting earnings to the individual participant account balances. Most other Plan administrative expenses are absorbed by the Company. (f) Use of Estimates - The preparation of financial statements in conformity with accounting principles generally accepted in the U.S. requires the Plan administrator to make estimates and assumptions that affect the reported 10 amounts of net assets available for plan benefits at the date of the financial statements and the reported amounts of changes in net assets available for plan benefits during the reporting period. Actual results could differ from those estimates. (g) Risk and Uncertainties - The Plan invests in various investments, including common investment funds, mutual funds, common stock of the Company and investment contracts. Investments, in general, are exposed to various risks, such as interest rate, credit, and overall market volatility. Due to the level of risk associated with certain investments, it is reasonably possible that changes in the values of certain investments will occur in the near term and that such changes could materially affect the amounts reported in the financial statements. Note 3. Tax Status The Internal Revenue Service has determined and informed the Company by a letter dated Aug. 25, 2003, that the Plan and related trust are designed in accordance with the applicable sections of the Code. It is the intention of the Company to adopt any amendments necessary to maintain the qualified status of the Plan. Note 4. Plan Termination Provisions Upon termination of the Plan in its entirety, each participant is entitled to receive, in accordance with the terms of the Plan, the entire balance in the participant account. The Company has no intention to terminate the Plan. Note 5. Withdrawals and Distributions Withdrawals from participants' account balances will be made to participants while they are employed due to an election made by certain participants, reaching age 59-1/2 for certain participants or 70-1/2, or requests due to special "hardship" circumstances. Distributions from the Plan will be made upon termination of employment (by retirement, death, disability or otherwise) if the participant's account balance is less than $5,000. If the participant's account balance exceeds $5,000, the participant may elect to defer payment until he or she is age 70-1/2. Distributions can be either in the form of a lump sum or substantially equal annual installments. The unpaid portion of all loans made to the participant, including accrued interest, will be deducted from the amount of the participant account to be distributed. Distributions payable to participants at Dec. 31, 2003 and 2002 were $0 and $222,154, respectively. Distributions payable are not recorded in the accompanying financial statements, however, they are recorded in the Plan's Form 5500 (refer to Note 11). Note 6. Derivative Financial Instruments The Plan did not invest in any material derivative financial instruments during the years ended Dec. 31, 2003 and 2002. Note 7. Other Investment Information Investments held which were greater than 5% of the Plan's net assets available for plan benefits as of Dec. 31 were as follows: 2003 2002 ---------------- -------------- Alliant Energy Corporation Common Stock* $89,235,309 $52,468,184 (non-participant directed: $48,442,726 and $26,213,052, respectively) (participant directed: $40,792,583 and $26,255,132, respectively) American Express Trust Equity Index Fund III* 72,695,049 56,853,595 The Growth Fund of America 61,585,565 42,640,545 American Express Trust Long-Term Horizon (65:35) Fund* 31,904,378 27,051,550 The Brown Capital Management Small Company Fund 26,633,723 16,565,951 PIMCO Total Return Fund 20,219,670 21,384,606 * Represents party known to be a party-in-interest to the Plan. 11 During 2003, the Plan's investments, including gains and losses on investments acquired and disposed of, as well as held during the year, appreciated in value as follows: Alliant Energy Corporation Common Stock $28,689,853 American Express Trust Equity Index Fund III 16,225,289 The Growth Fund of America 14,786,100 The Brown Capital Management Small Company Fund 7,302,216 American Express Trust Long-Term Horizon (65:35) Fund 5,501,045 Putnam International Growth Fund 2,816,496 Dodge & Cox Stock Fund 2,776,239 Vanguard Mid-Cap Index Fund 468,548 Dreyfus Premier Emerging Markets Fund 382,638 Evergreen Small Cap Value Fund 304,187 American Express Trust Income Fund I 278,177 American Express Trust Long-Term Horizon (80:20) Fund 117,482 PIMCO Total Return Fund 83,657 American Express Trust Short-Term Horizon (25:75) Fund 49,056 American Express Trust Bond Index Fund II 7,016 ---------------------- Net appreciation in fair value of investments $79,787,999 ====================== Note 8. Non-Participant Directed Investments Information about the net assets and the significant components of the changes in net assets relating to the non-participant directed investments was as follows: As of Dec. 31, Net Assets: 2003 2002 ---------------------- ---------------------- Alliant Energy Corporation Common Stock $48,442,726 $26,213,052 American Express Trust Money Market Fund I 605,615 464,894 Contributions receivable 424,518 -- Investment income receivable 441 558 ---------------------- ---------------------- $49,473,300 $26,678,504 ====================== ====================== For the Year Ended Changes in Net Assets: Dec. 31, 2003 ----------------------- Employer contributions $6,936,742 Results of investment activity: Investment income 1,777,793 Net appreciation in fair value of investments 15,186,682 Transfers to participant directed investments (298,306) Distributions to participants (808,115) ----------------------- $22,794,796 ======================= Note 9. Related Party Transactions Certain Plan investments are shares of mutual funds and common trust funds managed by an affiliate of the Trustee and shares of common stock of the Company. As of Dec. 31, 2003 and 2002, the Plan held 3,583,747 and 3,170,283 shares of Alliant Energy Corporation common stock, respectively. These transactions qualify as party-in-interest. 12 Note 10. Amendments and Changes to the Plan On April 1, 2003, the Plan was amended to allow Alliant Energy Neenah, LLC (a subsidiary of Resources) employees who were actively employed on Jan. 31, 2003 to participate in the Plan. Note 11. Reconciliation to Form 5500 Distributions payable to participants are not included in the accompanying financial statements, however, they are recorded in the Plan's Form 5500. The following table reconciles net assets available for plan benefits per the financial statements to the Form 5500 as filed by the Company for the year ended Dec. 31, 2003 and 2002: 2003 2002 -------------------------- -------------------------- Net assets available for plan benefits per financial statements $400,889,639 $294,072,374 Adjustments: Benefits requested not yet paid -- (222,154) -------------------------- --------------------------- Amounts reported per Form 5500 $400,889,639 $293,850,220 ========================== =========================== The following table reconciles changes in net assets available for plan benefits per the financial statements to the Form 5500 as filed by the Company for the year ended Dec. 31, 2003: Distributions to Participants --------------------------- Amounts reported per financial statements ($11,551,768) Adjustments: Changes in benefits requested not yet paid 222,154 --------------------------- Amounts reported per Form 5500 ($11,329,614) =========================== Note 12. Subsequent Events Effective March 1, 2004, the Plan replaced the Vanguard Mid-Cap Index Fund with the State Street Global Advisors Mid-Cap Index Fund. 13 ALLIANT ENERGY CORPORATION 401(k) SAVINGS PLAN FORM 5500, SCHEDULE H, PART IV, LINE 4i - SCHEDULE OF ASSETS (HELD AT END OF YEAR) AS OF DECEMBER 31, 2003 Identity of issue, borrower, Description of investment including maturity date, Current lessor, or similar party rate of interest, collateral, par or maturity value Cost Value --------------------------------- --------------------------------------------------------------------- ----------- ------------ Interest Bearing Cash American Express Trust Money Market Fund I*, 4,132,841 shares $4,132,841 $4,132,841 Primary Reserve Fund, 39,889 shares 39,889 39,889 Registered Investment Companies Evergreen Small Cap Value Fund, 83,689 shares 1,486,127 1,785,913 The Growth Fund of America, 2,509,599 shares 47,359,686 61,585,565 PIMCO Total Return Fund, 1,887,924 shares 20,367,334 20,219,670 Dodge & Cox Stock Fund, 127,389 shares 11,773,840 14,494,303 The Brown Capital Management Small Company Fund, 895,853 shares 19,831,451 26,633,723 Vanguard Mid-Cap Index Fund, 222,295 shares 2,482,046 2,918,734 American Express Trust Short-Term Horizon (25:75) Fund*, 35,410 shares 628,083 678,847 American Express Trust Long-Term Horizon (65:35) Fund*, 2,729,903 shares 26,815,786 31,904,378 American Express Trust Long-Term Horizon (80:20) Fund*, 39,158 shares 814,593 924,476 Dreyfus Premier Emerging Markets Fund, 200,486 shares 3,086,897 3,370,171 EuroPacific Growth Fund, 438,319 shares 10,767,440 13,118,882 Common/Collective Trusts American Express Trust Equity Index Fund III*, 2,449,624 shares 70,511,230 72,695,049 American Express Trust Income Fund I*, 83,217 shares 4,611,795 5,299,028 American Express Trust Investment Grade Bond Fund*, 305,535 shares 4,470,587 4,788,649 American Express Trust Bond Index Fund II*, 18,086 shares 245,445 247,548 Corporate Stocks: Common Alliant Energy Corporation common stock*, 3,583,747 shares 87,615,743 89,235,309 Corporate Bonds Americredit 2002-B A3, 3.78%, 2/12/07 198,268 200,488 AMCAR 2002-C AR, 3.55%, 2/12/08 99,982 101,797 CWL 2003-5 AF5, 3.61%, 4/25/30 149,997 151,055 COAFT 2002-B A4A, 3.32%, 4/15/09 101,969 101,837 COMET 2003-A4 A4, 3.65%, 7/15/11 100,449 100,000 FSPC T-17 A4 ABS HEL, 6.93%, 1/25/26 665,902 689,105 HART 2003-A A3, 2.33%, 11/15/07 149,998 150,539 LB-UBS 2002-A2, 4.90%, 6/15/26 200,995 210,643 LB-UBS 2002-C4 A2, 4.02%, 9/15/26 151,423 152,705 LBUBS 2003-C3 A1, 2.60%, 5/15/27 189,526 186,357 LBUBS 2003-C7 A2, 4.06%, 9/15/27 150,747 150,778 LBUBS 2003-C8 A2, 4.21%, 11/15/27 150,744 152,130 MBNA 2003-A11, 3.65%, 3/15/11 199,643 200,156 MSC 2003-IQ4 A1, 3.27%, 5/15/40 68,501 65,821 RALI SER 2003-QS4 ABS, 5.50%, 9/25/33 295,082 293,467 RALI 2003-QR19 CB2, 5.75%, 10/25/33 258,477 257,031 RASC 2003-KS9 A13, 3.25%, 12/25/28 149,979 150,094 RASC 2003-KS10 A13, 3.25%, 5/25/29 149,997 149,977 WAMU 2003 AR12 A6, 3.96%, 2/25/34 99,997 99,531 WESTO 2002-2 A4, 4.50%, 2/20/10 155,865 155,254 WESTO 2003-4 A3, 2.39%, 1/22/08 149,994 150,375 WBCMT 2003-C8 A2, 3.89%, 11/15/35 150,745 150,670 Government and Agency Obligations FHLMC Gold #E91326, 6.50%, 9/1/17 132,821 132,836 FHLMC Gold #E96180, 4.50%, 5/1/13 186,128 182,611 FHLMC Gold #E96579, 4.50%, 6/1/13 195,118 191,490 FHLMC MTN, 3.525%, 12/20/07 370,000 375,967 FHLMC, 3.00%, 10/27/06 300,000 301,390 FHLMC Gold #C66932, 6.00%, 5/1/32 114,852 118,476 FHLMC Gold #B10258, 5.00%, 10/1/18 328,009 328,702 FHLMC Gold #B10776, 5.00%, 11/1/13 153,008 153,586 FHLB, 2.88%, 9/15/06 202,463 201,934 FHLMC 2393-A CMO, 5.50%, 4/15/30 70,253 70,571 FHLMC, 2.38%, 4/15/06 452,800 451,775 FHLMC, 2.75%, 8/15/06 607,129 605,505 FHLMC, 3.63%, 9/15/08 251,973 251,298 FNMA Benchmark, 4.25%, 7/15/07 184,523 182,515 FNMA, 2.25%, 5/15/06 399,188 399,998 FNMA, 3.88%, 11/17/08 349,202 351,246 Fannie Mae, 3.75%, 1/23/08 250,000 250,410 FNMA #251887, 7.00%, 5/1/28 49,835 50,369 FNMA 15yr #252260, 6.00%, 3/1/10 726,201 767,179 FNMA #254187, 5.00%, 12/1/08 587,104 605,166 FNMA #254291, 7.00%, 4/1/17 200,081 200,755 FNMA #254757, 5.00%, 3/31/13 179,436 176,908 FNMA #545701, 7.00%, 7/1/12 286,865 285,574 FNMA #545864, 5.50%, 8/1/17 288,640 296,070 FNMA #555655, 4.46%, 7/1/33 295,251 295,149 FNMA #555740, 4.50%, 9/1/18 285,169 291,946 FNMA #640996, 7.50%, 5/1/32 116,511 116,361 FNMA #648349, 6.00%, 6/1/17 136,634 137,181 FNMA #679357, 5.50%, 1/1/18 1,126,296 1,118,843 14 ALLIANT ENERGY CORPORATION 401(k) SAVINGS PLAN FORM 5500, SCHEDULE H, PART IV, LINE 4i - SCHEDULE OF ASSETS (HELD AT END OF YEAR) AS OF DECEMBER 31, 2003 (Continued) Identity of issue, borrower, Description of investment including maturity date, Current lessor, or similar party rate of interest, collateral, par or maturity value Cost Value --------------------------------- -------------------------------------------------------------- ------------- --------- FNMA 2002-W3 A3, 6.00%, 7/25/24 275,741 287,459 FNMA 2002-W5 A6, 6.00%, 8/25/32 251,758 259,010 FNMA 2002-W4 A3, 5.30%, 5/25/42 401,000 416,409 FNMA 2002-W9 A3, 5.00%, 8/25/42 201,141 208,018 FNMA CMO 03-W2-2A6, 5.50%, 7/25/42 310,313 309,108 FHLMC 2492-B, 5.50%, 5/15/13 378,127 374,814 FNMA #200394, 5.50%, 7/25/23 313,172 315,651 FHLMC SF1 A3, 2.00%, 12/15/08 150,082 149,912 FHLMC 2617 HD, 7.00%, 6/15/16 153,394 152,163 FNMA 2003-112 AB, 4.00%, 6/25/16 147,179 148,955 FNMA 2003-109 CX, 4.00%, 7/25/16 150,791 149,682 FNMA 2003-106 B, 4.50%, 10/25/19 204,063 201,235 FNMA 2003-W16 AF3, 2.91%, 1/25/29 149,997 148,711 FNMA 2003-133 GB, 8.00%, 12/25/26 109,578 109,688 FHLMC 2657 NT, 5.00%, 1/15/16 156,117 157,298 FHLMC 2663 BA, 4.00%, 8/15/16 95,524 97,295 FHLMC 2672 NT, 5.00%, 2/15/16 208,289 209,745 FHLMC 2662 DB, 5.00%, 2/15/16 156,047 157,301 FHLMC 2685 MX, 4.00%, 7/15/16 151,242 149,945 FHLMC 2681 PJ, 5.00%, 10/15/15 313,734 312,459 FHLMC 2688 DE, 4.50%, 2/15/20 151,359 150,633 FHLMC 2716 UA, 4.50%, 7/15/20 299,250 302,260 FNMA #685433, 6.50%, 3/1/33 256,982 255,515 FNMA ARM #704534, 3.75%, 6/1/33 142,551 145,740 FNMA #705304, 4.91%, 6/1/33 197,193 198,645 FNMA ARM #722781, 4.29%, 9/1/33 492,890 498,361 FNMA #725090, 4.82%, 11/1/33 149,203 150,891 FNMA ARM #726155, 3.62%, 8/1/33 143,267 146,262 GNMA 2003-109 B, 3.22%, 9/16/21 149,334 148,875 GNMA 2003-36A, 2.93%, 10/16/20 97,742 97,499 GNMA 2003-22 A CMO, 2.75%, 6/16/21 77,165 77,938 RASC SER 2002-KS1, 5.86%, 11/25/29 319,781 309,402 VENDEE 2003-2 C, 5.00%, 7/15/20 103,406 103,791 U.S. Treasury Note, 5.63%, 2/15/06 438,250 431,078 U.S. Treasury Note, 5.75%, 11/15/05 385,820 375,785 U.S. Treasury Note, 1.75%, 12/31/04 251,201 251,260 U.S. Treasury Note, 1.25%, 5/31/05 2,207,913 2,214,095 U.S. Treasury Note, 2.63%, 11/15/06 3,612,833 3,622,701 U.S. Treasury Bond, 3.38%, 12/15/08 510,581 513,504 Investment Contracts Monumental Life Insurance Company, 3.71%, 12/31/50 Synthetic Guaranteed Investment Contract Wrapper - (49,656) Bank of America NA, 5.72%, 12/31/50 Synthetic Guaranteed Investment Contract Wrapper - (168,294) Rabobank International, 4.91%, 12/31/50 Synthetic Guaranteed Investment Contract Wrapper - (28,373) CDC Financial Products Inc., 2.95%, 12/31/50 Synthetic Guaranteed Investment Contract Wrapper - (34,837) JP Morgan Chase & Co., 3.75%, 12/31/50 Synthetic Guaranteed Investment Contract Wrapper - (39,533) UBS Warburg, 3.60%, 12/31/50 Synthetic Guaranteed Investment Contract Wrapper - (55,322) State Street Bank and Trust Company, 3.09%, 12/31/50 Synthetic Guaranteed Investment Contract Wrapper - (10,126) AIG Financial Products Corp., 3.07%, 12/31/50 Synthetic Guaranteed Investment Contract Wrapper - (121,985) United of Omaha, 1.30%, 5/20/05 2,002,242 2,002,242 John Hancock Life Insurance Company, 7.69%, 3/31/05 2,115,241 2,115,241 New York Life Insurance Company, 7.41%, 8/15/05 2,055,942 2,055,942 Hartford, 5.21%, 11/15/06 2,012,842 2,012,842 Protective Life Insurance Company, 6.12%, 6/15/06 2,065,677 2,065,677 United of Omaha, 5.45%, 9/9/04 1,016,874 1,016,874 Participant Promissory Notes Maximum loan -- $50,000 Various interest rates -- 5.0% to 10.5% Primarily maturing within 5 years 8,213,703 8,213,703 -------------- ---------------- $363,601,114 $400,268,084 (1) ============== ================ (1) The difference between the total current value on this Schedule H, Part IV, Line 4i and the total investments on the Statements of Net Assets Available for Plan Benefits is equal to accrued interest on the GIC's. * Represents party known to be a party-in-interest to the Plan. 15 ALLIANT ENERGY CORPORATION 401(k) SAVINGS PLAN FORM 5500, SCHEDULE H, PART IV, LINE 4j - SCHEDULE OF REPORTABLE TRANSACTIONS FOR THE YEAR ENDED DECEMBER 31, 2003 Identity of Party Involved and Total Number Total Value Total Number Net Selling Adjusted Cost Net Description of Assets of Purchases of Purchases (1) of Sales Price (1) of Assets Sold Gain (Loss) --------------------- ------------ ---------------- -------- ----------- -------------- ----------- ------------------------------------------------------------------------------------------------------------------------------------ Single Transaction Exceeds 5% of Value: None. ------------------------------------------------------------------------------------------------------------------------------------ Series of Transactions With Same Broker Exceeds 5% of Value: None. ------------------------------------------------------------------------------------------------------------------------------------ Series of Transactions In Same Security Exceeds 5% of Value: American Express Trust Money Market Fund I (2) 259 $49,941,833 412 $47,335,578 $47,335,578 $ - ------------------------------------------------------------------------------------------------------------------------------------ Single Transaction With One Broker Exceeds 5% of Value: None. ------------------------------------------------------------------------------------------------------------------------------------ (1) The purchase/selling price was equal to the fair value on the date of purchase/sale. (2) The Plan invests in two separate American Express Trust Money Market Fund I accounts. The total number of purchases above reflects the number of purchases from one of the accounts. The Trustee is unable to provide the number of purchases for the second account which is one of the underlying assets of the Synthetic GIC's. 16 SIGNATURES Pursuant to the requirements of the Securities Exchange Act of 1934, the Employee Total Compensation Committee, which administers the Plan, has duly caused this Annual Report to be signed on its behalf by the undersigned, thereunto duly authorized, on this 25th day of June, 2004. ALLIANT ENERGY CORPORATION 401(k) SAVINGS PLAN /s/ Jonathan C. Day -------------------- Jonathan C. Day The foregoing person is the Director - Total Compensation of Alliant Energy Corporation and the Chairman of the Alliant Energy Corporation Employee Total Compensation Committee. 17 EXHIBIT INDEX ALLIANT ENERGY CORPORATION 401(k) SAVINGS PLAN FORM 11-K Page Number in Sequentially Numbered Exhibit No. Exhibit Form 11-K ----------- ------- --------- 23 Independent Registered Public Accounting Firm Consent 19 18