Check the full article for a data broker company index
"Thanks to a new Vermont law requiring companies that buy and sell third-party personal data to register with the Secretary of State, we’ve been able to assemble a list of 121 data brokers operating in the U.S. It’s a rare, rough glimpse into a bustling economy that operates largely in the shadows, and often with few rules.Here are the data brokers quietly buying and selling your personal information | Fast Company
Even Vermont’s first-of-its-kind law, which went into effect last month, doesn’t require data brokers to disclose who’s in their databases, what data they collect, or who buys it. Nor does it require brokers to give consumers access to their own data or opt out of data collection. Brokers are, however required to provide some information about their opt-out systems under the law–assuming they provide one."