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Over the weekend, executives from public Internet companies Yelp and TripAdvisor noted a disturbing trend: Google searches on smartphones for their businesses had suddenly buried their results beneath Google’s own. It looked like a flagrant reversal of Google’s stated position on search, and a move to edge out rivals.

Nope, it’s a bug, claims Google. “The issues cited were caused by a recent code push, which we’re working quickly to fix,” a Google spokeswoman said.

In the meantime, the “issues” may be diverting tons of traffic from Google’s competitors. Some, particularly Google’s longtime rival Yelp, are not pleased. “Far from a glitch, this is a pattern of behavior by Google,” said its CEO Jeremy Stoppelman.

In contention here is something called “navigational search” — queries when the searcher knows the destination but, out of ease or ingrained habit, goes to Google anyway. To find Southwest airline tickets, you type southwest.com into the search bar. You would expect to see results for Southwest rise to the top, perhaps under some paid ads from it or rivals. (This has treated Google well.)

On Sunday, Stoppelman flagged what looked like a new wrinkle in Google’s navigational search: Queries for “TripAdvisor Hilton” were leading with Google’s local results, its OneBox, above results for TripAdvisor the website. Stephen Kaufer, TripAdvisor’s CEO, chimed in.

https://twitter.com/kaufer/status/668549459308097536

Both men’s companies are complainants in the European Union case against Google for anticompetitive behavior. Their complaints center on the claim that Google intentionally promotes its own products — in their case, local search results — over others. Yelp recruited legal scholar Tim Wu, once a Google defender, to make this case. (In the antitrust cases, Google has argued that its search products are driven by users’ needs, not competition.)

Another docket in Yelp’s case comes from Google’s older internal communications. Emails surfaced during the FTC antitrust investigation of Google, dug up by the Wall Street Journal, reveal then-VP Marissa Mayer detailing the search giant’s use of “co-occurrence signals.” When searches triggered competing websites to rise, Google’s algorithm automatically surfaced its own products. (Here are the FTC docs.)

The concern here is that the TripAdvisor search marks the first time co-occurrence signals are triggered for the mobile OneBox. That would not just surface Google’s results, but place them above others. As of Tuesday morning, the TripAdvisor search was replicated for searches with other hotel names, as well as those for Yelp. It’s unclear how long Google’s fix will take.

Here, courtesy of Yelp, are the before and after:

The company shared internal research showing that around a third of navigational searches on Google for “Yelp” and an accompanying term were directed away from Yelp. Foursquare and ZocDoc saw more than a fifth of their traffic diverge and TripAdvisor saw a whooping 50.54 percent “misdirected” mobile visits, according to Yelp.

TripAdvisor declined to comment further.

“Google is now intentionally providing the wrong answers for local searches on the mobile Web,” said Yelp’s Stoppelman. “This is not good for consumers or for competition but good for maintaining Google’s monopoly.”

Update: TripAdvisor CEO Kaufer sent over this statement on Wednesday: “It’s clear that Google continues to seek ways to manipulate its search results to benefit Google’s own interests. Google’s behavior to suppress the most useful and relevant content is both deceptive and anti-consumer.”

Update II: On Thursday morning, Google sent word that the bug has been fixed. It is on my Android phone; local searches for TripAdvisor and Yelp put those sites back at the top.