WhatsApp promises not to sell your data. Why you may be skeptical

For global messaging sensation WhatsApp, the privacy brouhaha that followed its sale to Facebook came as a rude surprise. Soon after the $19 billion deal was announced, consumer privacy groups asked federal regulators to investigate the merger for potential consumer harms and possibly block the deal.

Some users are threatening to leave the service. WhatsApp founders tried to deflate concerns that user data may be used for advertising. But it will be hard for the messaging service to convince users who thought they had signed up to service that would never use data for targeted advertising, privacy advocates say. Any deal with Facebook comes with the baggage of the social networking giant's troubled history on privacy.

"They took Facebook's money, and now one of them has a seat on their board," said Jeff Chester, head of Center for Digital Democracy, a privacy group that along with the Electronic Privacy Information Center recently filed a complaint against the merger to the Federal Trade Commission. Jan Koum, who co-founded WhatsApp with Brian Acton, will join Facebook's board once the deal closes.

Facebook has repeatedly changed privacy policies on users, having the effect of a slow boil that constantly pushes the comforts of users who are at this point too reliant on the network to leave, some consumer groups say. The merger of Facebook and WhatsApp brings together two companies with diametrically opposing business models and philosophies on consumer data. Facebook's success is tied directly to how much data it collects about its users and sells for advertising.