American Century Ultra Fund - I Class (TWUIX) 425 Business combination disclosure

                                  FILED BY:  AMERICAN CENTURY MUTUAL FUNDS, INC.
                                                  PURSUANT TO RULE 425 UNDER THE
                                              SECURITIES ACT OF 1933, AS AMENDED

                           SUBJECT COMPANY:  AMERICAN CENTURY MUTUAL FUNDS, INC.
                                       SEC REGISTRATION STATEMENT NO. 333-140907



                          AMERICAN CENTURY INVESTMENTS
                                4500 MAIN STREET
                           KANSAS CITY, MISSOURI 64111


March 6, 2007

Securities and Exchange Commission
100 F Street, N.E.
Washington, DC 20549

RE:  American Century Mutual Funds, Inc. (the "Registrant")
         1933 Act File No. 333-140907

Ladies and Gentlemen:


     We are filing  this notice to correct our  inadvertent  filing  pursuant to
Rule 425 under the  Securities  Act of 1933,  as amended,  submitted on March 5,
2007 with accession  number  0000100334-07-0000019.  The filing was submitted in
error and should be disregarded.

     Should you have any  questions or concerns  regarding  this filing,  please
contact the undersigned at (816) 340-3224.

Sincerely,

/s/ Christine J. Crossley
- ----------------------------------------
Christine J. Crossley
Corporate Counsel