Advertising, PR and marketing conglomerates Publicis and Omnicom are in "late-stage" merger talks, according to a report by Bloomberg.

Paris-based Publicis, parent to MSLGroup, and New York-based Omnicom (Ketchum, Fleishman-Hillard, Porter Novelli) could create a $30B giant surpassing rival WPP in size.

Bloomberg, citing a person with knowledge of the situation, said the talks could still collapse.