The news will come as a blow to WPP - CITIC was Grey Global Group's Chinese joint-venture partner until the day of the announcement.
Omnicom's DDB China will merge with the CITIC subsidiary CITIC Guoan to form DDB Guoan Communications. Omnicom will own a majority stake in the joint venture. The partnership doubles the size of the DDB network in China overnight.
CITIC was formed in 1978. Its investments range from telecoms and broadcasting to airlines. The company has assets valued at $90 billion.