6.0% Cumulative Conv. Preferred Stock Filed pursuant to 424 (b) (3) Registration No. 333-104394 4,600,000 SHARES OF CHESAPEAKE ENERGY CORPORATION 6.00% CUMULATIVE CONVERTIBLE PREFERRED STOCK (LIQUIDATION PREFERENCE $50 PER SHARE) AND COMMON STOCK, (PAR VALUE $.01 PER SHARE) PROSPECTUS SUPPLEMENT NO. 9 DATED JULY 16, 2004 TO PROSPECTUS DATED OCTOBER 1, 2003 The selling securityholders table on pages 31 through 35 of the prospectus is amended by this supplement no. 9 to read as follows. Number of Number of Number of Shares of Shares of Shares of Preferred Number of Preferred Number of Number of Common Stock Stock Shares of Stock to be Shares of Shares of to be Owned Beneficially Preferred Owned After Common Stock Common Stock After Owned Prior Stock Being Completion Beneficially Being Completion to the Offered of the Owned Prior to Offered of the Name Offering Hereby Offering Offering Hereby Offering Aftra Health Fund 2,000 2,000 0 9,721 9,721 0 AIG/National Union Fire Insurance 5,700 5,700 0 27,705 27,705 0 Alexiann Brothers Medical Center 2,500 2,500 0 12,151 12,151 0 Aloha Airlines Non-Pilots Pension Trust 1,700 1,700 0 8,263 8,263 0 Aloha Pilots Retirement Trust 875 875 0 4,253 4,253 0 Alpine Associates 121,950 121,950 0 592,738 592,738 0 Alpine Partners, L.P. 16,200 16,200 0 78,740 78,740 0 Alta Partners Discount Convertible Arbitrage Holdings LTD 85,000 85,000 0 413,143 413,143 0 Alta Partners Holdings LDC 77,200 77,200 0 375,231 375,231 0 Amaranth LLC 55,250 55,250 0 268,543 268,543 0 American Skandia Trust 10,800 10,800 0 52,493 52,493 0 American Century Capital Portfolios, Inc. - Small Cap Value Fund 50,000 50,000 0 243,025 243,025 0 Argent Classic Convertible Arbitrage (Bermuda) Fund, Ltd. 131,800 131,800 0 705,549 640,614 64,935 Argent Classic Convertible Arbitrage Fund, L.P. 41,758 41,758 0 300,367 202,965 509,649 Argent LowLev Convertible Arbitrage Fund II, LLC 2,600 2,600 0 12,637 12,637 0 Argent Classic Convertible Arbitrage Fund II, L.P. 13,042 13,042 0 222,572 63,391 159,182 Argent LowLev Convertible Arbitrage Fund LLC 26,300 26,300 0 410,298 127,831 282,467 Argent LowLev Convertible Arbitrage Fund LTD 85,600 85,600 0 630,344 416,059 214,286 Arkansas Teachers Retirement 45,235 45,235 0 219,865 219,865 0 Attorney's Title Insurance Fund 1,375 1,375 0 6,683 6,683 0 B.C. McCabe Foundation 3,800 3,800 0 18,470 18,470 0 B.G. I. Global Investors, c/o Forest Investment Mgmt., L.L.C. 6,800 6,800 0 33,051 33,051 0 Bancroft Convertible Fund, Inc. 12,500 12,500 0 60,756 60,756 0 Baptist Health of South Florida 8,610 8,610 0 41,849 41,849 0 Bear, Stearns & Co., Inc. 5,000 5,000 0 24,303 24,303 0 Boilermakers Blacksmith Pension Trust 4,925 4,925 0 23,938 23,938 0 BP Amoco PLC Master Trust 11,556 11,566 0 56,168 56,168 0 C & H Sugar Company, Inc. 2,200 2,200 0 10,693 10,693 0 Calamos Market Neutral Fund-Calamos Investment Trust 70,000 70,000 0 340,235 340,235 0 CGNU Life Fund 15,000 15,000 0 72,908 72,908 0 Class C Trading Company, Ltd. 7,000 7,000 0 34,024 34,024 0 Commercial Union Life Fund 20,000 20,000 0 97,210 97,210 0 Conseco Fund Group - Convertible Securities Fund 2,000 2,000 0 9,721 9,721 0 Convertible Securities Fund 1,350 1,350 0 6,562 6,562 0 Credit Suisse First Boston, L.L.C. 18,915 18,915 0 91,936 91,936 0 Daimler Chrysler Corp. Emp. #1 Pension Plan dtd 4/1/89 41,600 41,600 0 202,197 202,197 0 DBAG London 487,843 487,843 0 2,890,641 2,371,161 519,480 Delaware PERS 5,475 5,475 0 26,611 26,611 0 Drury University 350 350 0 1,701 1,701 0 Ellsworth Convertible Growth and Income Fund, Inc. 12,500 12,500 0 60,756 60,756 0 Engineers Joint Pension Fund 4,370 4,370 0 21,240 21,240 0 Equitec Group LLC 15,000 15,000 0 72,908 72,908 0 F.R. Convt. Sec. Fn. 575 575 0 2,795 2,795 0 Family Service Life Insurance Co. 4,000 4,000 0 19,442 19,442 0 Fidelity Destiny Portfolio: Destiny II 194,800 194,800 0 946,825 946,825 0 Fidelity Financial Trust: Fidelity Convertible Securities Fund 31,400 31,400 0 152,620 152,620 0 Fidelity Hastings Street Trust: Fidelity Contra Fund II 29,000 29,000 0 789,255 140,955 648,300 Forest Fulcrum Fund, LLP 17,100 17,100 0 83,115 83,115 0 Forest Global Convertible Fund Series A-5 76,500 76,500 0 371,828 371,828 0 Forest Multi-Strategy Master Fund SPC, on behalf of Series F, Multi Strategy Segregated Portfolio 9,400 9,400 0 45,689 45,689 0 Franklin and Marshall College 3,500 3,500 0 17,012 17,012 0 Gasner Investor Holdings Ltd. 17,000 17,000 0 82,629 82,629 0 Guardian Life Insurance Co. 126,000 126,000 612,423 612,423 0 Guardian Pension Trust 10,000 10,000 0 48,605 48,605 0 Guggenheim Portfolio Co. XV, L.L.C. 20,000 20,000 0 97,210 97,210 0 Hawaiian Airlines Employees Pension Plan-IAM 625 625 0 3,038 3,038 0 Hawaiian Airlines Pension Plan for Salaried Employees 100 100 0 486 486 0 Hawaiian Airlines Pilots Retirement Plan 1,500 1,500 0 7,291 7,291 0 HFR TQA Master Trust c/o TQA Investors, L.L.C. 10,350 10,350 0 115,241 50,306 64,935 Hillbloom Foundation 700 700 0 3,402 3,402 0 Hotel Union & Hotel Industry of Hawaii Pension Plan 5,118 5,118 0 24,876 24,876 0 ICI American Holdings Trust 1,250 1,250 0 6,076 6,076 0 ING American Century Small Cap Value Portfolio 900 900 0 4,374 4,374 0 ING Convertible Fund 15,000 15,000 0 72,908 72,908 0 ING VP Convertible Port 150 150 0 729 729 0 Intl. Truck & Engine Corp Non Contributory Retirement Plan Trust 9,100 9,100 0 44,231 44,231 0 Intl. Truck & Engine Corp Retirement Plan for Salaried Employee's Trust 13,800 13,800 0 67,075 67,075 0 Jefferies & Company Inc. 219 219 0 1,064 1,064 0 JMG Capital Partners, L.P. 176,807 176,807 0 859,370 859,370 0 JMG Triton Offshore Fund Ltd. 261,343 261,343 0 1,270,258 1,270,258 0 KD Convertible Arbitrage Fund L.P. 73,000 73,000 0 354,817 354,817 0 Key Span Foundation 1,150 1,150 0 5,590 5,590 0 LDG Limited 10,350 10,350 0 115,241 50,306 64,935 Lincoln National Convertible Securities Fund 10,000 10,000 0 48,605 48,605 0 LLT Limited 7,700 7,700 0 58,854 37,426 21,429 Lord Abbett Investment Trust - LA Convertible Fund 6,000 6,000 0 29,163 29,163 0 Lord Abbett Series Fund, Inc. Bond Debenture 4,100 4,100 0 19,928 19,928 0 Lyxor Master Fund, c/o Argent/LowLev CB 33,000 33,000 0 225,332 160,397 64,935 Lyxor Master Fund, c/o Forest Investment Mgmt., L.L.C. 34,100 34,100 0 165,743 165,743 0 Mainstay Convertible Fund 22,600 22,600 0 109,847 109,847 0 Mainstay VP Convertible Portfolio 9,100 9,100 0 44,231 44,231 0 McMahan Securities Co., L.P. 46,400 46,400 0 225,527 225,527 0 Merrill Lynch Insurance Group Bond Debenture 500 500 0 2,430 2,430 0 Met Investors Bond Debenture Fund 50,000 50,000 0 243,025 243,025 0 Morgan Stanley & Co. Incorporated 125,000 125,000 0 607,563 607,563 0 NSTAR Pension Plan 2,000 2,000 0 9,721 9,721 0 Met Investors Series Trust Bond Debenture 27,000 27,000 0 131,234 131,234 0 National Fuel & Gas Company Retirement Plan 2,850 2,850 0 13,852 13,852 0 Nations Convertible Securities Fund 173,650 173,650 0 844,026 844,026 0 New York Life Insurance Company 35,800 35,800 0 174,006 174,006 0 New York Life Separate Account No. 7. 500 500 0 2,430 2,430 0 Nicholas Applegate Capital Management Conv. Income Fund 259,801 259,801 0 1,262,763 1,262,763 0 Nicholas Applegate Capital Management Conv. Mutual Fund 9,170 9,170 0 44,571 44,571 0 Nicholas Applegate Capital Management Convert & Income 2 218,500 218,500 0 1,062,019 1,062,019 0 Norwich Union Life & Pensions 30,000 30,000 0 145,815 145,815 0 Nuveen Preferred and Convertible Fund JQC 105,000 105,000 0 510,353 510,353 0 Oxford, Lord Abbett & Co. 34,000 34,000 0 165,257 165,257 0 Phoenix Lord Abbett Bond Debenture Fund 200 200 0 972 972 0 Physicians Life 2,375 2,375 0 11,544 11,544 0 Privelege Portfolio 81CAV 50,000 50,000 0 243,025 0 Prudential Insurance Co. of America 325 325 0 1,580 1,580 0 Putnam Convertible Income - Growth Fund 101,000 101,000 0 490,911 490,911 0 Quattro Fund Ltd. 40,000 40,000 0 194,420 194,450 0 2 R.B.C. Alternative Assets, L.P., c/o Forest Investment Mgmt., L.L.C. 6,800 6,800 0 33,051 33,051 0 Radcliffe SPC, Ltd. For and on behalf of the Class A Convertible Crossover Segregated Portfolio 64,000 64,000 0 311,072 311,072 0 Ramius, L.P. 3,000 3,000 0 14,582 14,582 0 RCG Baldwin, L.P. 10,000 10,000 0 48,605 48,605 0 RCG Halifax Master Fund, LTD. 10,000 10,000 0 48,605 48,605 0 RCG Latitude Master Fund, LTD. 75,000 75,000 0 364,538 364,538 0 RCG Multi Strategy A/C L.P. 75,000 75,000 0 364,538 364,538 0 RCG Multi Strategy Master Fund, LTD. 8,000 8,000 0 38,884 38,884 0 Relay 11 Holdings, c/o Forest Investment Mgmt., L.L.C. 4,300 4,300 0 20,900 20,900 0 San Diego City Retirement 9,450 9,450 0 45,932 45,932 0 San Diego County Convertible 20,620 20,620 0 100,224 100,224 0 SG Cowen Securities Corporation 30,000 30,000 0 145,815 145,815 0 Silver Convertible Arbitrage Fund, LDC 12,800 12,800 0 62,214 62,214 0 Southern Farm Bureau Life Insurance 9,375 9,375 0 45,567 45,567 0 Sphinx Convertible Arbitrage Fund SPC 4,006 4,006 0 19,471 19,471 0 Sphinx Convertible Arbitrage, c/o Forest Investment Mgmt., L.L.C. 2,100 2,100 0 10,207 10,207 0 Standard Pacific Capital 50,000 50,000 0 243,025 243,025 0 State of Oregon/Equity 17,250 17,250 0 83,844 83,844 0 State of Oregon/SAIF Corporation 54,000 54,000 0 262,467 262,467 0 State Street Bank Custodian for GE Pension Trust 26,800 26,800 0 130,261 130,261 0 Susquehanna Capital Group 250,000 250,000 0 1,215,125 1,215,125 0 Syngenta AG 900 900 0 4,374 4,374 0 Topanga XI 43,000 43,000 0 209,002 209,002 0 Total Fina Elf Finance USA, Inc. 4,600 4,600 0 22,358 22,358 0 TQA Master Fund, LTD 34,460 34,460 0 167,493 167,493 0 TQA Master Plus Fund, LTD 34,490 34,490 0 167,639 167,639 0 UBS O'Connor LLC f/b/o O'Connor Global Convertible Arbitrage Master Limited 50,000 50,000 0 243,025 243,025 0 UBS O'Connor LLC f/b/o O'Connor Global Convertible Portfolio 7,500 7,500 0 36,454 36,454 0 UBS Securities, LLC 22,650 22,650 0 110,090 110,090 0 Univest Convertible Arbitrage Fund Ltd., c/o Forest Investment Mgmt. L.L.C. 1,407 1,407 0 6,839 6,839 0 US Bank, FBO Benedictine Health Systems 2,825 2,825 0 13,731 13,731 0 Viacom Inc. Pension Plan Master Trust 396 396 0 1,925 1,925 0 Wake Forest University 6,355 6,355 0 30,888 30,888 0 White River Securities, L.L.C. 5,000 5,000 0 24,303 24,303 0 WPG Convertible Arbitrage Overseas Master Fund 18,000 18,000 0 87,489 87,489 0 WPG MSA Convertible Arbitrage Fund 4,500 4,500 0 21,872 21,872 0 Writers Guild Convertible Fund 77,200 77,200 0 375,231 375,231 0 Wyoming State Treasurer 11,105 11,105 0 53,976 53,976 0 Xavex Convertible Arbitrage 10 Fund 16,400 16,400 0 381,011 79,712 301,298 Xavex Convertible Arbitrage 2 Fund 11,200 11,200 0 158,334 54,438 103,896 Xavex Convertible Arbitrage 4 Fund c/o Forest Investment Mgmt. L.L.C. 800 800 0 3,888 3,888 0 Xavex Convertible Arbitrage 7 Fund c/o TQA Investors, LLC 5,000 5,000 0 24,303 24,303 0 Xavex Convertible Arbitrage No. 5 9,000 9,000 0 43,745 43,745 0 Zurich Institutional Benchmark Management, c/o Quattro Fund 10,000 10,000 0 48,605 48,605 0 Zeneca Holdings Trust 1,325 1,325 0 6,440 6,440 0 Zurich Institutional Benchmark Master Fund, LTD 30,705 30,705 0 266,118 149,242 116,877 Zurich Institutional Benchmark Master Fund, LTD c/o Argent 6,400 6,400 0 119,419 31,107 88,312 Zurich Institutional Benchmarks Master Fund, LTD c/o TQA Investors, L.L.C. 10,350 10,350 0 50,306 50,306 0 Zurich Master Hedge Fund c/o Forest Investment Mgmt., L.L.C. 10,200 10,200 0 49,577 49,577 0 The stated amounts, to the extent they describe common stock issuable upon conversion of the holder's preferred stock, assume conversion of all of the holders' preferred stock at a conversion ratio of 4.8605 shares of our common stock per share of preferred stock. This conversion ratio, however, will be subject to adjustment as described under "Description of the Preferred Stock - Conversion Price Adjustment". As a result, the number of shares of our common stock issuable upon conversion of the preferred stock and, therefore, attributable to holders of preferred stock, may increase or decrease in the future. 3