SAN FRANCISCO (Reuters) - Shares of Twitter Inc TWTR.N tumbled 6 percent on Thursday after reports that Fox News had not tweeted for three weeks sparked fears of a backlash by conservatives protesting a perceived liberal bias by the company.

A 3D printed Twitter logo is seen in front of displayed stock graph in this illustration picture made in Zenica, Bosnia and Herzegovina, February 3, 2016. REUTERS/Dado Ruvic

Twenty-First Century Fox Inc's FOXA.O Fox News has not tweeted to its 18.3 million followers since Nov. 8, an apparent boycott of the social network, Politico reported on Wednesday.

It stopped tweeting after activists used Twitter to post the home address of prominent news host Tucker Carlson, media news site Mediaite reported on Nov. 9. Demonstrators targeted Carlson’s home in Washington with a protest and shouted threats, he told the Washington Post.

Fox News and Twitter declined to comment.

Facebook FB.O and other social media networks are facing calls for increased regulation and criticism of their handling of user data and the role their platforms have played in a divisive U.S. political climate in recent years.

Still, analysts viewed Thursday’s stock drop as an over-reaction.

“I think the people who want to be alarmist will say this is the first step toward losing the conservatives, and that this could snowball. But at this point, I think that’s overly alarmist, and I don’t see it as a big deal. So I see this as a buying opportunity,” said FBN analyst Shebly Seyrafi, who has an “outperform” rating on Twitter’s stock.

Last month, Twitter posted quarterly results that far exceeded Wall Street’s estimates even after it purged millions of fake accounts used for disinformation and other abuses.

Conservatives in the past have complained about having their accounts unfairly closed by Twitter, and about alleged political bias in the California company’s rules.

Twitter this week reinstated the account of conservative commentator Jesse Kelly after U.S. Senator-elect Josh Hawley said that Congress should investigate the company after it closed Kelly’s account, and the account of Canadian feminist Megan Murphy.

The company said on Wednesday that it had suspended an account for impersonating Russian President Vladimir Putin.