Last month, a pair of security researchers discovered an unprotected server that contained personal information belonging to over one billion people. The data was collected by an aggregator known as People Data Labs, which is a completely legitimate data analytics company. There are thousands of these companies across the country, and for the most part, they trade in your information without you ever interacting with them or giving permission to them directly.
The problem with this is, as illustrated by this breach, there is no way for you to control a) who has your data, and b) how they handle their operational security, meaning that extensively detailed personal information about you is spread out across dozens of companies, many of whom likely do not follow basic security procedures. It's only a matter of time before your data is exposed by a company like PDL, and as of right now, there is very little being done to prevent that. The main protection against breaches like this is to limit the amount of data that you enter into the many websites that you visit, carefully read privacy policies, and take a more active role in protecting your personal information. Even then, however, there are still ways for your data to be gobbled up by aggregators such as PDL.
If you want to learn more about this, read the main article HERE.