Barry Salzman, who has headed up the unit - which had made up a core part of the company's revenues in its early days -- will be replaced by Jeffrey Silverman. Salzman was not immediately available for comment.
Silverman has been with the company's U.S. media business for four years, a company spokesman said.
The move comes as the New York-based company attempts to diversify its revenue streams in a bid to make money at a time ad spending has dried up amid economic uncertainty.
"If you took away our media business, we'd be a profitable company," Chief Financial Officer Bruce Dalziel said at a JP Morgan conference earlier in the week. "We're having the most challenges in our international media business."
Salomon Smith Barney analyst Lanny Baker said in a research note Thursday that the rise in DoubleClick's shares this week was partly attributed to the perception the company might exit the ad sales network part of its media business.
"We believe that the Media unit's relatively small size, structurally lower gross profit margins, current unprofitability and long-term competitive dynamics mean that it is nonessential to DoubleClick's long-term growth strategy," Baker said in the note.
The company spokesman would not comment on the perception that DoubleClick may exit the media business.
In October, DoubleClick cut much of its media staff as it contended with the downturn. The company, a market darling during the dot-com boom, has been trimming jobs throughout the year.
It has also been increasing its focus on its e-mail marketing and technology business and been buying up smaller players. It revised a deal to buy e-mail marketing firm MessageMedia Inc. in October, slashing its price by almost 80 percent to about $9 million.
Shares of DoubleClick closed off 6 cents at $8.34 but were up nearly 19 percent since the beginning of this week.