Yelp has long been accused of acting like the Tony Soprano of online reviews. Companies claim that Yelp favors advertisers by emphasizing their search results and reviews. Some businesses say Yelp has tried to persuade them to buy ads by offering to make negative reviews disappear — or tried to strong-arm them by threatening to delete positive comments. A few companies banded together in 2010 to sue the firm over such practices. And some Yelp shareholders have sued, too, claiming the company inflated its revenues by coercing businesses to advertise. More than 2,000 complaints about Yelp have also piled up at the Federal Trade Commission, which has scrutinized Yelp’s ad-sales tactics and “recommendation” software, used to highlight reviews deemed the most useful to consumers.