Prospectus Supplement No. 6 Filed Pursuant to Rule 424(b)(3) (To Prospectus Dated May 19, 2000) Registration No. 333-35412 Prospectus Supplement Dated August 30, 2000 This prospectus relates to the resale by the holders of our: o $450,000,000 principal amount of 5.0% convertible notes due 2010, and o the shares of Class A common stock issuable upon conversion of the notes. This prospectus supplement should be read in conjunction with, and may not be delivered or utilized without, the prospectus dated May 19, 2000. The terms of the notes are set forth in the prospectus. The information in the table appearing under the heading "Selling Securityholders" on page 33 in the prospectus is hereby amended by adding the information below with respect to selling securityholders not previously listed in the prospectus or in any amendments or supplements thereto, and by superceding the information with respect to selling securityholders previously listed in the prospectus or in any amendments or supplements thereto that are listed below: Number of Shares Percentage of Principal Amount of Class A Common Number of Class A at Maturity of 5.0% Stock Issuable Shares of Class Common Stock Notes Beneficially Upon Conversion of A Common Stock Outstanding as Owned That May the 5.0% Notes That Beneficially of August 28, Selling Securityholders be Sold May be Sold Owned** 2000*** ------------------------- ------------------- ------------------- --------------- -------------- Bankers Trust Company Trustee for Chrysler Corp. EMP #1 Pension Plan DTD 4/1/89 $6,315,000 122,621 -- * Chartwell Investment Partners $0 0 -- * Credit Suisse First Boston Corporation (1) $830,000 16,116 -- * Franklin and Marshall College $361,000 7,009 -- * Liberty View Funds L.P. $750,000 14,563 -- * Penn Treaty Network America Insurance Co. $515,000 10,000 -- * State Street Bank Custodian for GE Pension Trust $3,119,000 60,563 -- * STI Capital Management $0 0 -- * Van Kampen Convertible Securities Fund (1) $0 0 -- * Van Kampen Harbor Fund (1) $0 0 -- * =========== ========= === == TOTAL $11,890,000 230,872 -- ** Less than 1%. ** In addition to the shares issuable upon conversion of the notes. *** Includes shares issuable upon conversion of the notes and additional shares beneficially owned as of August 28, 2000. (1) Entity shown in the table, or an affiliate of the entity, was one of the initial purchasers of these notes and/or other notes of the Company that were sold in a private placement. The initial purchasers acquired such notes at a discount. In addition, some of these entities or their affiliates have participated in other offerings of securities by the Company and/or have performed other banking services for which they have received fees.