Shares for the world's most popular Internet search engine went over $600 for the first time on Oct. 8, and have increased 51 percent this year before Wednesday, according to Bloomberg.

“One of the reasons that Google has been such a success story is not only because it's taken market share from its competitors, but also to some extent it's created new opportunities and new markets,” Scott Kessler, Standard & Poor's analyst in New York, told Bloomberg. He also said the earnings increases are “very strong, but the valuation is pretty stretched.”

Google continues to dominate the Internet search market, and has recently seen a windfall, thanks to online and mobile advertising.

Google shares are the fifth-highest among U.S. companies, and are more than twice the price as shares of Microsoft Corp., Intel Corp. and Hewlett-Packard Co.

California-based Google has risen more than $30 billion in stock market value to more than $218 billion since passing the $600 per share mark the second week of October. Rival Yahoo is valued at $41.6 billion, according to Bloomberg.