• by Mark Walsh  @markfwal, February 28, 2014

In its annual report filed Friday, Yahoo reiterated that the company is focused on building products “focusing on mobile first.” It boasts of having over 400 million monthly mobile users, making up more than half its 800 million users overall globally (excluding Tumblr).

But in the same 10-K report filed with the Securities & Exchange Commission, the Web giant conceded that its revenue from mobile is still insignificant. “Currently, our revenue from mobile is not material and our competitors have mobile revenue significantly greater than ours,” states the report.

Under the risk factors section of the filing, Yahoo also cautions: “If we are unable to develop products for mobile devices that users find engaging and that help us grow our mobile revenue, our competitive position, our financial condition and operating results could be harmed.”

The annual report underscores how much Yahoo has riding on mobile as key to restoring much-needed growth, but also how far it has to go to monetize increased usage on devices. Consider that a rival such as Facebook already gets more than half of its ad revenue from mobile advertising, and mobile last year made up roughly a of Google’s total ad revenue, per eMarketer.

Under CEO Marissa Mayer, Yahoo has taken steps over the last year and a half to ramp up its mobile operations by overhauling apps for key properties like Flickr and Yahoo Weather, as well as the $1.1 billion acquisition of Tumblr and some 30 less costly startups to bring in new talent and technology.

In the 10-K report, Yahoo also highlights ad initiatives, including the rollout of its mobile-friendly Stream Ad unit in 2013. More recently, its announced  a simplified ad platform that gives advertisers a single dashboard for running different types of Yahoo ad formats across mobile and desktop properties.

Last week, the company launched its Gemini marketplace combining native and mobile search engine advertising, allowing marketers to buy, manage and optimize native and search ad spend in one place.

During Yahoo’s fourth-quarter conference call, Mayer acknowledged the dearth of mobile ad revenue to date, but asserted that its ad products have the potential to monetize better in mobile than on the desktop. She said Stream Ads are seeing “positive traction” from advertisers and users, but offered little evidence to support those claims.

By contrast, LinkedIn recently reported that its own native unit -- Sponsored Updates -- now makes up 13% of ad sales since being widely launched in mid-2013 (with two-thirds of that amount coming from mobile). . Yahoo has not released any similar data in relation to the performance of Stream Ads, making it difficult to know whether it's gaining traction or not.

If 2013 was about building up its mobile content offerings and audience, Yahoo this year has to show it can make those slick-looking apps and native ads begin to pay off. Mayer suggested as much when she said in the Q4 earnings call: “We remain confident that there is a big opportunity for Yahoo and we will continue to focus and invest in mobile monetization in 2014.”

Whether Yahoo provides more insight on the level of mobile monetization in the next quarterly earnings call will be interesting to see. If not, it will only raise more questions about whether the mobile push under Mayer will help revive revenue growth, especially on the display side. Sales from display advertising fell 6% in the fourth quarter from a year ago.