Update 8/1: WBBM began its simulcast on 105.9 at 8:10am as Chicago Mayor Rahm Emmanuel and Illinois Governor Pat Quinn were in studio to flip the proverbial switch.

In what looks to be a shot at Merlin Media’s female-centric “FM News 101.1“, the station is emphasizing its sports reports at :15 and :45 after the hour.

Listen to the debut of Newsradio 105.9 at FormatChange.com.

Original Report 7/14: As first reported by Time Out Chicago’s Robert Feder via Twitter, CBS is preparing for the new competition about to be brought by Merlin Media by flipping AC “Fresh 105.9” to a simulcast of All-News 780 WBBM on August 1.

The move comes as Merlin assumes operations at what is now Modern Rock “Q101” WKQX at midnight with an expected flip to News as WIIN.

CBS runs a similar All-News simulcast in San Francisco, which saw 740 KCBS rise to the top of the ratings after beginning to simulcast on 106.9 KFRC. In Chicago the move is being made in attempt to protect WBBM’s top spot.

Read the press release here.