Facebook-owned messaging service WhatsApp is facing a fine of 225 million euros - or $267 million - over privacy breaches. Ireland's data protection regulator imposed the penalty after an investigation spanning more than two years.
WhatsApp has signaled it will lodge an appeal.
Ireland's Data Protection Commission found the company breached transparency rules about the sharing of personal information with other Facebook entities.
The European Union's data protection laws require companies to inform individuals how their data is used - and get their approval.
WhatsApp is disputing the finding. In a statement, the firm maintains it has worked to ensure the information it provides is transparent and comprehensive.
The fine is the second-largest for breaching EU data rules. Amazon was hit with an $886 million penalty in July.