Google's anti-trust probe by the European Union could hurt the search giant's growth, pocketbook and its reputation. When news of the nine-count probe was broken by Reuters Tuesday, Google shares tumbled about $10, or only 1.5%.

Officials at Google headquarters in Mountain View, California, didn't respond to to today's report but made available prior comments by senior executives that they "respect" the investigation process and would cooperate fully. As well, the executives said Google had always been "transparent" in its dealings.

The EU had previously acknowledged examining at least four complaints of alleged anticompetitive practices against Google, but Reuters reported there are now five more, including three brought by "national regulators." Small European companies had previously complained about Google as had Microsoft, whose Bing search engine competes against Google.

If proved, any antitrust charges against Google would cloud its reputation, first laid out by co-founders Sergey Brin and Larry Page, to "do no evil." In the U.S., the Federal Trade Commission has said it is also looking at Google's practices.

Microsoft, which the EU previously found had engaged in anti-competitive practices, was fined $600 million in 2004. As a result, the Redmond, Washington-based software giant was forced to stop selling its Windows Media Player along with its Windows operating system installed on PCs.

In May, Microsoft's nine-year oversight of its practices by a U.S. district court judge ended, following a consent decree signed with the Clinton Administration, which initially sued to break up Microsoft in 1998.

Because Google's search engine far outpaces competitors like Bing, as well as Yahoo and China's Baidu, any negative findings could lead to fines, new practices and forestall adoption of Google as a default browser by government agencies, at least in the EU.

Like Microsoft, though, Google has plenty of cash to mount a legal defense, as well as pay any fines or settlements. In the second quarter, Google's cash and short-term investments exceeded $39.1 billion. More than 54% of revenue came from international customers, with 11% alone from Britain.

In late U.S. trading, Google shares were at $598 or 7% below their 52-week high.