Peter Sherman,
exec VP, Omnicom

Omnicom made much of luring Peter Sherman back to the holding company after he defected to WPP's JWT last June. (Before going to JWT, he was exec VP at BBDO in Europe.) Omnicom CEO John Wren specifically called out Mr. Sherman on Friday's analyst and press call after it was announced that the merger was off as an example of how the company has managed to recruit people during the merger talks. It remains to be seen what his responsibilities will be within Omnicom once again on its own.

Troy Ruhanen,
exec VP, Omnicom

John Wren recruited Troy Ruhanen, who was chairman-CEO of the Americas at BBDO, to take on a role at the holding-company level in October. He is now exec VP of Omnicom Group, where he works on collaboration and innovation for the company's clients. It is unclear what his role will be now that the merger has been scuttled.

Chuck Brymer,
President-CEO, DDB Worldwide;
Mark O'Brien, president,
DDB North America

While DDB is in the midst of hot pitches for Cigna and TD Ameritrade, new business has been slow going at the Omnicom shop. Chuck Brymer succeeded the late Ken Kaess as president-CEO in 2006 and was handpicked by Mr. Wren. A relative unknown coming from brand consultancy Interbrand Group, Mr. Brymer was seen as a surprise choice, given how high-profile Mr. Kaess was in his five years atop DDB. It's possible that Mr. O'Brien, next in line and armed with experience in Asia-Pacific, could succeed Mr. Brymer at a shop that desperately needs a jolt on the new-business front.

Tom Carroll,
president-CEO, TBWA Worldwide

TBWA and Mr. Carroll are facing pressure to go after new business now that the Pepsi brand left the L.A. office (Gatorade remains) and Infiniti is still in review. The Omnicom shop is also under the microscope when it comes to Apple, given Samsung's charge in a lawsuit against the Cupertino, Calif., company that Apple nearly fired TBWA in 2013. Add to this a change of the guard at TBWA/Chiat/Day, Los Angeles. In April, it tapped Luis DeAnda as president following Carisa Bianchi's departure. Chief Creative Officer Stephen Butler was promoted to the post that same month to succeed John Norman, who left for Translation in February.

Brent Smart,
CEO, Saatchi New York

All eyes are on Saatchi's flagship office in New York, which seems to be teetering after MillerCoors cut ties with the Publicis shop. The agency had been the lead on Miller Lite and Miller Fortune, but things started turning sour after a big portion of Miller Lite was moved to a collection of WPP shops. New-business growth has slowed down. The shop is trying to expand its relationship with Walmart, and much will rely on Mr. Smart, appointed CEO in November. He's looking to strengthen the shop's creative capabilities, with the hire of a chief creative, Jay Benjamin, from sibling Leo Burnett New York.

Rishad Tobaccowala, chief strategy and innovation
officer, ViVaki

ViVaki, having achieved its original goal of educating Publicis shops on all things digital when it formed in 2008, laid out new goals last year prior to the merger announcement: data-driven marketing, next-generation commerce and storytelling, and a geographic focus on China, India and the Americas. It's unclear what role Mr. Tobaccowala would have played in a combined holding company, as Omnicom also had Digital CEO Jonathan Nelson overseeing that strategy at its networks. But industry-watchers are eager to see what strategies and innovations Mr. Tobaccowala will bring to the holding company.

Arthur Sadoun,
Global CEO, Publicis Worldwide

Will he be Maurice Levy's successor? He may be unlikely to earn that designation by the end of next year, but if he makes a promising start, Publicis' supervisory board may consider again asking Mr. Levy, 72, to stay awhile longer.