• by Steve McClellan  @mp_mcclellan, April 13, 2015

On Monday morning, Pivotal Research senior analyst Brian Wieser issued a note downgrading the ratings he had for WPP, Omnicom and Publicis, urging investors to sell their shares in those companies and to exit the sector for the foreseeable future.

Investors took Wieser’s advice — driving those stocks down, along with the stock of Interpublic Group, which Wieser downgraded to a “hold” position.

Wieser’s advice was based on what he termed the “emerging concerns among marketers around different forms of agency rebates in the United States.”  

The stocks dropped significantly more than the Dow, which was down 0.45% on the day. Among the big four holding companies, Omnicom was down the most on a percentage basis, with a decline of 1.53% to $77.42 on the New York Stock Exchange. IPG was down 0.92% on the same exchange.

Publicis was down 0.85% on the Euronext exchange, while WPP American Depository Receipts on the NASDAQ exchange fell 0.69%. Havas Group, not mentioned in Wieser’s report, was down 0.55% on the Euronext Exchange.

MDC Partners, also not mentioned in Wieser’s report, emerged unscathed in today’s trading. In fact, the Toronto-based holding company, which trades on the NASDAQ Exchange, was up 3.11% to $27.54.

Dentsu also appeared unaffected by Wieser’s note — the company posted a slight gain (0.17%) on the Tokyo Exchange. 

Reps for WPP, IPG, Omnicom and Publicis didn't answer queries about Wieser's note to investors.