Shares of Google Inc. (GOOG) slipped Thursday after the world's most popular Internet search engine warned for the second time in a week that its fourth-quarter revenue growth rate is likely to slow from previous quarters.

Shares of Google fell as low as $165.73 on the Nasdaq and closed at $167.54, down $4.96 or nearly 3 percent on the day. Since its Aug. 19 initial public offering, the stock has traded in a range of $95.96 to $201.60.

Google shares had dropped more than 6 percent on Tuesday after the company released some 39.1 million new shares into the market as a so-called "lockup" period expired for employees and other insiders.

Still, the shares are up roughly 13 percent since Oct. 21, when the company reported better-than-expected first quarter results.

In a regulatory filing with the Securities and Exchange Commission (search), the Mountain View, Calif.-based company said that its sequential growth rate would probably decline in the fourth quarter versus the third quarter because of intensifying competition and an "inevitable" slowdown as the business gets bigger.

Its sequential revenue growth rate was 7.5 percent in the second quarter versus the first quarter and 15.1 percent in the third quarter compared with second quarter.

Google also warned that its advertising revenues could be hurt by its decision to remove online ads that generate low levels of interest — a move Google says should improve the overall Internet experience of its users.

The statement was nearly identical to a warning the company made Monday, in another routine regulatory filing.