The European Commission has launched an anti-trust probe into Google, following complaints that it is abusing its dominance of the search market.
Rival search providers – including Microsoft and UK price comparison firm Foundem – have complained that Google's gives “preferential placement” to its own services and downgrades theirs.
The EC said in a statement that it would look into allegations that Google lowered the quality score for sponsored links of competing vertical search services, such as Foundem’s.
It would also focus on allegations that Google imposed exclusivity obligations on advertising partners, preventing them from placing competing ads on their web sites.
Google said in a blog post that “given our success and the disruptive nature of our business, it’s entirely understandable that we’ve caused unease among other companies and caught the attention of regulators.
“We respect their process and will continue to work closely with the Commission to answer their questions.”
The commission pursued Microsoft for more than a decade over its dominance of the browser market, imposing $2.4 billion in fines on the software firm.
Google’s Nasdaq stock fell 4.54% and a further 0.23% in after-hours trading to $554.45.