SAN FRANCISCO -- Once Google's Achilles' heel, mobile has now turned the tech giant into Wall Street's darling. Shares of Alphabet, Google's parent company, are trading up more than 9 percent on Friday, following third-quarter earnings that show the tech giant has finally turned around its mobile business. 

For much of 2014 and early 2015, shareholders and analysts were unsure about Google's ability to dominate the mobile advertising market the way it did with desktops during the 2000s, but on Thursday, the tech company blew past analysts' revenue estimates and credited its mobile business for the success. It's the second straight quarter Google has done that, and Wall Street is emphatic.

"Despite iPhone 6, Google has managed to keep growing Android,” said Johnny Won, founder of Hyperstop, a consultancy firm. "Google might struggle at times with unifying the Android ecosystem, but Android is a conduit for Google's search business, which is the core of how Google makes money with mobile revenue."

Newly appointed Google CEO Sundar Pichai spoke on the company's earnings call for the first time, instilling confidence, many said, and boasting that Google now has six products with more than 1 billion users, those being Search, YouTube, Maps, Chrome, Android and Google Play, the company's app store, which recently began selling ads. Additionally, Pichai announced that Google has now indexed more than 100 billion deep links for third-party apps, which means Google Search is now capable of searching for more content found within apps, not just on the Web. 

"This is not a change in performance, but rather a change in confidence," said Jamie Hill, CEO of adMarketplace, a search advertising platform. "Google claims to have drastically improved app search, and cites the ability to bridge the gap between mobile apps and the mobile Web."

But Google isn't out of the woods yet. For starters, the company doesn't actually break out the performance of its mobile advertising business. That means analysts and investors have to simply take the company's word that mobile is doing well without seeing any statistics that prove the point.

"We still have no idea how mobile is really performing at Google because the company still isn't providing any sort of transparency into the key metrics for the mobile business," said Jan Dawson, chief analyst at Jackdaw Research. "We still have no idea how big that business is, how profitable it is or exactly how fast it's growing."

Earlier this year, Google announced that users in 10 markets, including the United States, were now conducting more searches on mobile than desktop. That seems to signal that Google is doing a good job of growing mobile, but unless the company gives shareholders more data, it remains unclear whether Google has actually fixed its problems with mobile or if consumers' overall migration from PCs to smartphones is masking the issues. 

"Google is benefiting from consumer behavior shifts and accessibility to mobile and capitalizing by constantly refining its offerings tied to mobile search," said Tom Edwards, chief digital officer of agency business at Epsilon, a global marketing company.

Additionally, the search giant is facing fierce competition in the mobile display advertising space from chief rival Facebook and others that have begun to eat into Google's slice of the pie. Google remains the king of the $72 billion global mobile-advertising sector, with a 33.7 percent market share, but that's down from 38.4 percent in 2014, according to eMarketer.

"The question is just whether broad trends like the ongoing shift to apps instead of the Web on mobile will dampen this growth over time and drive it to other ad companies like Facebook and Twitter," Dawson said. "Unless Google starts providing more transparency around its mobile business, we're going to have to continue to take executives' word for it that it's going well and there aren't any problems, even as they fail to provide any real numbers to make those claims more concrete."