The7stars has handled Coral since 2011 and Blue 449 has looked after Ladbrokes since 2007. Ladbrokes is believed to spend slightly more on media than Coral.
The bookmakers completed their merger in November last year amid a wave of consolidation in the sector following Paddy Power Betfair’s tie-up.
It is thought that Coral executives played a leading role in the media review and observers said the fact they ran a closed process indicated that both bookmakers were happy with the incumbents.
A spokeswoman for Ladbrokes Coral confirmed the appointment.