Yahoo is a latecomer to mobile and CEO Marissa Mayer knows it.

Speaking at the TechCrunch Disrupt conference in New York today, Mayer described mobile as one of Yahoo’s “biggest missed opportunities” and outlined what she’s done and plans to do going forward in order to keep Yahoo competitive in the mobile market.

“Last year was really the year where we began to make our investment in mobile and we’re late and we’re behind,” Mayer said. "When I got to Yahoo, mobile was everyone's hobby and it was no one’s job.”

Since taking the helm, Mayer has rallied a team of more than 500 mobile designers and engineers dedicated to making Yahoo a leader in mobile technology. She said the company is looking to appeal to users' daily habits – gaming and communication.

"When you look at how people are spending time on phones … a lot of it is communications or games based. "Something like 50 percent of the top hundred [mobile apps] are games, so we do have a new games platform and we obviously have communication tools. We’re hopeful those communication tools like Tumblr, like Yahoo Mail will be up with the top apps.”

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Just a quick look at Apple’s App Store shows just how far behind Yahoo is. Google Maps, Docs, Search and YouTube apps are all among the 20 most popular apps. Facebook has three apps in the top 20 – the main Facebook app, Messenger and Instagram. As of today, Yahoo’s Mail app was No. 43.

Recent success on Tumblr—which Yahoo acquired for $1.1 billion—is a big step in the right direction and an example of something Yahoo has really been able to get right by improving the mobile interface and increasing engagement.

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“More than 58 percent of Tumblr users engage with sponsored content. Forty-eight percent of them actually reshare it because the branded content is so good, so authentic, so interesting,” she said.

By the end of 2014 Mayer said Yahoo’s traffic will reach the crossover point with more users on mobile devices than PCs.

“Mobile is approximately doubling along every metric we have. Traffic, revenue, users. Were up to 430 million monthly users on mobile so we have the largest mobile audiences in the world already,” she said. “Now it's a matter of taking the content services that we have online and bringing them onto the phone in a really meaningful way.”

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