THE GLOBAL RECESSION is roughing up smaller advertising companies even more than their bigger rivals, a lesson being learned by two companies partially owned by French industrialist Vincent Bolloré.

Mr. Bolloré holds about 30% of media buyer Aegis Group PLC, which on Monday reported that first-quarter revenue fell 12%, excluding the effects of acquisitions, divestments and currency shifts.

Late Friday, Havas SA, where Mr. Bolloré holds a 32.9% stake and is also chairman, reported an 8.4% drop in first-quarter revenue, by the same measure.

At both companies, the problem is the same. Along with the rest of the industry, each has taken a hit as the recession has savaged corporate ad spending. At Aegis and Havas, however, the pain has been compounded by losses of key accounts and the heavy reliance of each on a single business in an industry led by more-diversified global giants.

"Small players get hit harder because they're more committed to a smaller number of clients," said RBS analyst Justin Diddams.

Last June, computer maker Dell Inc. dropped Havas's Euro RSCG Worldwide from its Asia-Pacific account in favor of
WPP

PLC, the world's biggest ad holding company by revenue. In November, auto-making allies Renault SA and Nissan Motor Co. switched their joint media-buying account from Aegis's Caret unit to the ad industry's No. 2 player, Omnicom Group Inc. of the U.S.

Even though the account losses were public knowledge, investors hadn't expected such disappointing first-quarter revenue at Aegis and Havas. Aegis shares fell 4.6% to 84.90 pence ($1.29) in London trading Monday, while Havas shares tumbled 15% to €1.96 ($2.64) in Paris.

Their performance is a blow to Mr. Bolloré, a shipping and transportation magnate who started investing in the media and ad businesses about five years ago. He has long argued that Havas and Aegis should merge or cooperate in some way to give them the scale to compete with bigger rivals.

Though global powerhouses like WPP, Omnicom and Paris-based Publicis Groupe have been pinched by the dropoff in ad and marketing spending, they have the advantage of diversification after gobbling up public-relations, direct-marketing and digital-advertising agencies in recent years

Last month, WPP reported that first-quarter revenue fell 5.8%, excluding the impact of acquisitions, divestments and currency movements. Publicis said its first-quarter revenue, on the same basis, slipped 4.4%

More than half of Dublin-based WPP's revenue comes from outside advertising and media buying, making its results less volatile, a long-stated goal of its chief executive, Martin Sorrell. Publicis has a large business in digital marketing, one of the few ad fields that is growing.

By contrast, Havas gets roughly 70% of its revenue from ad agency Euro RSCG. Aegis is dominated by its media-buying operations, which buy ad spots in bulk for clients.

During the credit boom, the media-buying industry grew rapidly as marketers sought advice on how to reach consumers via the Internet, cellphones, computer games and other new media. But the media-buying industry's reliance on commissions has left it vulnerable during the recession as companies reduce their ad spending and media owners charge less for ad space.

Aegis's executive chairman, John Napier, said his company's year-earlier first-quarter results were particularly strong, making comparisons with this year tough. He said the company can maintain profit margins this year by cutting executives' bonuses.

"We think we are in the right place and doing well in terms of new business wins," said Mr. Napier, who took control of Aegis last year, removing its chief executive in a move that analysts viewed as making a merger with Havas more likely.

Mr. Napier set out to improve relations with Mr. Bolloré and has decided to replace three members of the Aegis board. Mr. Bolloré recently dropped plans to get his own nominees appointed. Asked about his position on a possible merger with Havas, Mr. Napier said: "I don't have one."

Mr. Bolloré couldn't be reached for comment, and a spokesman for him declined to comment on Aegis's revenue.

Under Mr. Bolloré, Havas has promoted younger managers to try to expand its business, including David Jones, the head of its ad agencies. But the company was hurt in the first quarter by a 20% cut in marketing spending by its U.S. financial-services clients, Havas said in a statement.

—Kathy Sandler contributed to this article.

Write to Aaron O. Patrick at aaron.patrick@wsj.com