NEW YORK (CNN/Money) - Dan Rather will step down as anchor and managing editor of the CBS Evening News on March 9, 2005 after 24 years in the job.

Rather will give up the CBS Evening News anchor chair March 9.

Rather and CBS issued a statement Tuesday in which he said, "This past summer, CBS and I began to discuss this matter in earnest -- and we decided that the close of the election cycle would be an appropriate time (to leave the broadcast.)"

No successor was named in the announcement about Rather's departure. A spokesman for CBS said there was no timetable for the successor to be named.

CBS Evening News has consistently ranked third among the three major networks' evening news broadcasts in recent years. In the most recent week, it was watched by about 5.4 percent of U.S. homes, with about 7.5 million viewers, according to Nielsen Media Research. ABC reached about 6.8 percent of homes and NBC 7.6 percent.

CBS News came under fire during the presidential election when it reported it had documents written by a former National Guard commander that questioned President Bush's service in the guard during the Vietnam War. Rather initially defended the report, but the documents were later shown to be forgeries and CBS apologized, saying they should not have been used.

Rather's statement makes no mention of the National Guard document controversy.

CBS is a unit of media conglomerate Viacom (down $0.12 to $35.12, Research), which saw its shares up about 1 percent on the day but little changed following the midday announcement about Rather.

Rather succeeded Walter Cronkite as CBS Evening News anchor on March 9, 1981 and has held the position longer than any other U.S. network news anchor. He also serves as a full-time correspondent for 60 Minutes Wednesday. He was co-editor for the original 60 Minutes as well as the White House correspondent during the Johnson and Nixon administrations before becoming anchor.

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He will continue to work on 60 Minutes Wednesday in addition to other reports for CBS.

"I have always been and remain a 'hard news' investigative reporter at heart. I now look forward to pouring my heart into that kind of reporting full-time," he said in his statement.

NBC News anchor Tom Brokow is also leaving the anchor chair on Dec. 1. He will be succeeded by Brian Williams. NBC is a unit of General Electric Co. (Research)