Wall Street's one Google bear explains why he thinks the company is way overvalued

Google may dominate digital advertising now, but one Wall Street analyst said its unchallenged reign might be coming to an end.

Products like Amazon Alexa — which allows purchases by voice — and digital payments like Apple Pay are likely to disrupt the advertising industry and provide new methods for businesses to drive consumer spending, James Dix, securities analyst at Wedbush Securities, told CNBC's "Fast Money: Halftime Report" on Thursday.

That could especially impact Google's hallmark business, search, Dix said.

Sundar Pichai, CEO, Google
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Sundar Pichai, CEO, Google

"There's fundamental challenges to search's business model," Dix said. "Search is roughly half of the digital ad market. Is that going to be more or less in five years? It would seem as though its going to be tough for it to go up in market share. Fundamentally, that's a very high margin advertising product."

Dix is the only analyst listed in FactSet with a "sell" rating on shares of Google-parent Alphabet. His price target, $700 a share, is well below Thursday's price of around $852 a share, and the average target price of $966.29, from analysts surveyed by FactSet.

"The market needs more people who think the market is actually pricing in the expectations," Dix said.

The company will report earnings Thursday after the bell, when Wall Street is expecting adjusted earnings of $9.64 per Class A share on revenue of $25.23 billion, according to a Thomson Reuters consensus estimate. That would be up from a year ago, when the company reported $8.67 per share on revenue of $21.33 billion.

Google CEO Sundar Pichai has said he, too, expects the "device" to fade away in the future, with new mediums like artifical intelligence taking over. The company has released a voice-activiated product, Google Assistant, to aid with the transition.

Disclosure: Wedbush makes a market in securities of Alphabet