French advertising agency

Publicis

announced Tuesday that it bought British advertising group

Saatchi & Saatchi

(SSA)

for $1.89 billion in stock.

Once completed, the deal will create the world's

fifth-largest advertising agency.

Saatchi & Saatchi's American depositary receipts rose 30% Monday on the

rumor, closing up 7 11/16 at 33 1/16.

The deal continues a wave of consolidation in the advertising world. In May,

Young & Rubicam

(YNR)

was

acquired by the

WPP Group

(WPPGY)

of Britain, and earlier this year

Havas Advertising

bought

Snyder Communications

(SNC)

.