Google, one of the world's most valuable companies, crossed a new barrier late last week when its stock topped $US1000 a share for the first time.
It is now more expensive to buy a single share of Google stock than three iPad minis.
Investors were cheered by the tech giant's latest earnings report, which showed that internet users are increasingly clicking on the ads Google sells.
The company's revenue rose 18 per cent in the most recent quarter, compared with the corresponding period last year.
Google's earnings looked particularly strong after Yahoo, normally a primary competitor for online ad revenue, reported a lukewarm quarter in which it lost advertising market share to Google and Facebook.
That helped boost Google's stock nearly 14 per cent on Friday to close at $US1011.41, and makes rival Apple's stock - a mere $US508.89 a share - look downright cheap.
Pacific Crest Securities analyst Evan Wilson expects Google's stock to reach $US1135 a share.
Friday's rally sent Google's market capitalisation to $US337.39 billion, making it the third-largest publicly traded company behind ExxonMobile and Apple.
Google still faces hurdles. Its average ad rate - how much it charges for each click on an ad - fell 8 per cent during the quarter. It also continues to lose money on its Motorola purchase, which it has used to enter the smartphone market with the Moto X.
"It appears Google has not turned Motorola around, which is an ongoing disappointment," Mr Wilson said.
Google is struggling to reach customers through mobile devices and build its audience overseas. "These categories ... are the growth opportunity," Mr Wilson said in a note to investors.
Google has taken steps to address its mobile-advertising problem, simplifying the way it sells ads on mobile devices by allowing advertisers to buy campaigns for computers and smartphones at the same time.