By the time you read this, Facebook shares will likely have begun trading (or not). But the hoopla around the IPO was slightly dampened today, thanks to a mammoth class-action privacy lawsuit filed against it. The case combines 21 separate suits accusing Facebook of tracking users even when they weren't logged in, the Telegraph reports. They're looking for $15 billion—almost enough to wipe out the $16 billion Facebook stands to take in today.