Exhibit 99 October 12, 1999 Securities and Exchange Commission Washington, D.C. 20549 Re: Unicom Corporation, Commission File No. 1-11375; Commonwealth Edison Company, Commission File No. 1-1839 Amendment to Current Report on Form 8-K, Dated September 22, 1999, Filed October 12, 1999, Accession No. 0000950131-99-005626 Dear Sir or Madam: This Amendment to the Current Report on File 8-K, Dated September 22, 1999, Filed October 12, 1999 at 8:02 a.m., EDT, accession number 0000950131-99-005626, is being filed because the original filing contained a typographical error in the second paragraph under Item 7, where the fourth sentence read: "To the extent the fair value of Unicom's nuclear generating stations is ultimately determined to be GREATER than the June 30, 1999 book value of $6.9 billion, additional goodwill and/or an identifiable intangible asset will be recorded." This sentence is being corrected to read as follows: "To the extent the fair value of Unicom's nuclear generating stations is ultimately determined to be LESS than the June 30, 1999 book value of $6.9 billion, additional goodwill and/or an identifiable intangible asset will be recorded." Very truly yours, /s/ Ruth Ann M. Gillis Senior Vice President