Marissa Mayer's rampant acquisition spree during her first year at Yahoo is all about playing catch-up in the mobile space and investing in R&D, analysts say. But it won't be clear if her strategy is working for a while.
Yahoo has purchased 19 companies since Mayer took over last summer, including its recent $1.1 billion deal to buy Tumblr. And it's likely the company will continue to purchase companies at the same rate next year, said Martin Pyykkonen, an analyst at Wedge Partners.
However, unlike the Tumblr deal, which was primarily a way for the company to buy traffic and target a younger demographic, most of Yahoo's acquisitions so far have been aimed at acquiring talent that can help beef up the company's mobile strength, Pyykkonen said.
(Read more: Tumblr deal gives Yahoo social, mobile boost)
"Most of these fit one description, they are acqui-hires," Pyykkonen said. "A fair chunk of them are mobile, which is where there is the most sense of urgency and rightly so, they need to grow mobile traffic."
In other words, most of these purchases were really a way to snatch up talented engineers in order to weave them into Yahoo's development team to help build new mobile products and improve existing ones so that Yahoo can expand its mobile traffic.
Some of the companies Yahoo has purchased so far include Stamped, the iPhone app that allowed users to save and share recommendations; Ghostbird Software, a maker of iOS photography apps; and its most recent purchase Ztelic, a Beijing-based company that analyzes data on social networks—which it bought just last week.
And it's likely many more acquisitions are to come, analysts say.
"I don't think this is a one-year phenomenon, it does seem like Marissa is more inclined to bring in more external talent and companies than previous management. But I do think the $1 billion acquisitions like Tumblr will be very few and far between," said Mark Mahaney, an analyst at RBC. "I think there may be one large acquisition a year like that."
Pyykkonen also said it's likely Mayer will continue her shopping spree during her second year at Yahoo, but said the company may begin to shift in the type of firms it acquires, focusing more on content companies and investing more in the licensing of content.
But first the company is tackling the challenge of mobile, a space it is very late to enter, Mahaney said.
"The biggest trend is using mobile to access the Internet and there's no doubt that train left the station two or three years ago and has been gaining steam ever since. Yahoo has to catch up to that train," Mahaney said. "There is a gaping hole at Yahoo and she has to fill it."
Mahaney, who has a price target of $32 on Yahoo's stock with a rating of "outperform," said that it's like Mayer is buying all these companies to dramatically ramp up the company's R&D so that it can quickly catch up to its competitors like Google and Facebook in the mobile space.
But playing catch-up isn't easy and even if eventually Yahoo's acquisition strategy works and the new talent and R&D efforts are able to help boost the company's mobile traffic, Yahoo still faces serious competition when it comes to the real moneymaker, which is display and search advertising, Pyykkonen said.
"As we get into next year and as we look back at the third and fourth quarters, we can finally talk about mobile traffic growing subsequentially and it growing then partly due to acquisitions," Pyykkonen said. "But then again, Yahoo pales in comparison to Facebook's and Google's numbers."
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Facebook's mobile ad revenue accounted for 41 percent of its total ad revenue of $1.6 billion in the second quarter. And while Google's cost per click (CPC) were down in the second quarter, the company still saw 23 percent more clicks on its ads in the second quarter compared with the same quarter a year earlier, which helped offset the lower prices.
(Read more: Google earnings beat forecast, but revenue is light)
Yahoo's revenue from display and search advertising, however, continued to fall in the second quarter. Display revenue fell 12 percent from the same period a year ago and revenue from search dropped 9 percent.
But turnaround stories don't happen overnight. It's likely to be a multiyear process and evidence of a positive impact stemming from Mayer and her acquisition efforts likely won't be evident for at least a few more quarters, analysts said.
"The turnaround everyone is expecting, we haven't seen it yet." Pyykkonen said. "But it's a big ship to turn around in the harbor and get going in the right direction."
—By CNBC's Cadie Thompson. Follow her on Twitter @CadieThompson.