just took a tougher turn.
On Tuesday, the European Commission said it would launch an in-depth probe of the search giant's proposed takeover after an initial review of the deal brought up concerns about competition.
The commission set a deadline of 90 working days -- or until April 2 -- to decide whether to approve or block the deal. Its initial investigation raised concerns that a combined entity would wield too much power in the ad serving and online advertising markets.
Google's bid to acquire DoubleClick for $3.1 billion has drawn concern from many industry participants, the most vocal among them being
. Google reportedly prevailed over Microsoft in a heated bidding war for DoubleClick.
The DoubleClick acquisition is a key piece of Google's strategy to expand beyond the search ads that currently make up nearly all of its revenue.
Shares of Google were recently up $21.03, or 3.3%, to $653.10.