French advertising group Publicis said organic sales growth was a disappointing 1.0 percent in the third quarter, blaming mainly its focus on "other plans" - a reference to this year's failed merger with U.S.-based Omnicom.
"We are at the end of this cycle and very confident of the future," Chairman and Chief Executive Maurice Levy said in a statement, but he told reporters the third quarter result "does not match market expectations or our own".
"There are a number of factors behind this, mainly the fact that management was too focused on other plans and not enough on the short-term performance and growth," he added.
Read More Omnicom, Publicis deal was driven by ego: WPP
Levy also warned that full-year 2014 organic growth would be "not very different from the first nine months", when it was 1.5 percent. At the start of this year he had promised 4 percent.
Publicis' third-quarter performance compares badly with those of rivals that have reported so far. U.S-based Interpublic <IPG.N> delivered 6.3 percent organic growth and Omnicom scored 6.5 percent.
In September, Publicis shook up its management to prepare for life after the Omnicom deal fell through, parting company with its chief operating officer and teeing up the eventual departure of 72-year-old Levy himself.
In its September statement, the company reaffirmed its 2018 targets and said it would present a strategic plan to investors in October. On Thursday, the company set a tentative date of Nov. 7 for that presentation.
Read More Publicis shakes up management post-Omnicom deal failure
On a consolidated basis, including acquisitions but stripping out currency effects, revenue growth in the third quarter was 4.4 percent. It would have been 4.6 percent had exchange rates remained constant.
Other factors that dragged on the company's performance included the tough economic conditions in some emerging markets and in Europe, it said.
Its Razorfish digital agency also had problems with reduced business from two major accounts, those with Motorola and Blackberry, but despite this the digital division continued to increase its share of overall revenue, climbing 9.1 percent in the first nine months while analogue business fell 3.1 percent.
The $35 billion merger with Omnicom would have seen the pairing overtake WPP as the world's biggest advertising company. It fell apart over leadership conflicts that deepened during delays to tax and antitrust approvals.
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