Google faces a "difficult road" next year as it continues to adapt its model to mobile technology, the founder of a technology-focused hedge fund said Wednesday.
The "secular change" to mobile from desktop, which companies like Facebook have handled well, will challenge the technology giant in 2015, said Eric Jackson, founder and managing partner of Ironfire Capital.
"I think most of us thought Google made the leap, but I think there are some real question marks facing them in their business," Jackson told CNBC's "Squawk on the Street."
Facebook's "app install ads" places advertisements for mobile applications within the user's news feed on the Facebook app. The model smoothed Facebook's transition to mobile, Jackson said.
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Google holds the largest share of mobile ad revenue, with more than 40 percent of total revenue in 2014, according to Ad Age. But Google's share of the market decreased about 6 percent from 2013, while Facebook's increased 2 percent to roughly 18 percent.
Google did not immediately respond to CNBC's request to comment on its mobile strategy.