Google's stock price sank below 448 dollars per share on Tuesday but was slightly above 463 dollars in after-hours trading at 0300 IST (on Wednesday), representing a 17 per cent drop for the day.
Investors evidently fear the comScore figures signal an end to Google's years of exponential revenue growth. Google was founded in 1998 by Stanford University students Serge Brin and Larry Page. Its stock price rocketed after its initial public offering price of 85 dollars per share in August of 2004.
Consistently strong earnings and its crown as king of Internet search drove the price to nearly 750 dollars per share in October of last year.
Google's quarterly profits have topped a billion dollars, with most of the money coming from Internet ads that advertisers only pay for if clicked on to activate online links.
However, Google has been confronted with concerns about "click fraud," bogus clicking on Internet ads by competitors or crooks.
Google has explained while discussing earnings in recent quarters that it is taking steps to reduce click fraud, and to improve relevance and reduce numbers of ads displayed on search pages.