You may not know much about the companies exposing your personal information. But they know a lot about you.

Here's a fun question to pose at the family dinner table: have you ever heard of Alteryx? Whether you have or not, chances are good that it has heard of you. Alteryx is a data analytics company that makes its money by repackaging data that it has collected from different sources. And it became the latest reminder of how much data little-known companies have collected on us — and how little oversight there is over the security of that data. Data collection and analysis is a strong and growing multibillion dollar business, with thousands of firms. Alteryx, which is considered a relatively small data collection company, reported $34.2 million in revenue in its last quarterly report. Bigger names such as Acxiom — which was the victim of a hack in 2005 that exposed 1.6 billion customer records — often report at least $900 million in revenue per year.