Bob Sirott has left WMAQ Channel 5 as its main news anchor.

Channel 5 Vice President of News Frank Whittaker issued a memo to station staff Thursday saying, "Bob Sirott is leaving NBC 5 News, effective today."

Sirott had been with the station since early 2006 as weekend news anchor and had been groomed to replace the retiring Warner Saunders as the station's main news anchor alongside Allison Rosati by gradually taking on new assignments with the weekday evening and 10 p.m. newscasts.

Yet after Saunders retired last month, no formal statement was forthcoming from station management about Sirott being named top anchor, as the two sides reportedly negotiated a new deal. Those negotiations apparently broke down this week.

Sources at the station acknowledged the split was "economics-driven" and insisted both sides were "disappointed" a compromise couldn't be reached.

Sirott will continue on as midday host at WGN 720-AM "while pursuing other opportunities," according to Whittaker.

Channel 5 will rotate in various staffers as co-anchor alongside Rosati on its 10 p.m. news until someone is formally named to replace Saunders.

Sirott was the star disc jockey on WLS 890-AM in its Top 40 heyday in the '70s, but shifted into TV in the '80s. He enjoyed stints as host of the irreverent "Fox Thing in the Morning" on WFLD Channel 32 and the more staid "Chicago Tonight" on WTTW Channel 11 before joining Channel 5.