The Data Brokers
Who actually buys and sells the metadata extracted from your living room?
LiveRamp
A major player in identity resolution. They take offline data (like store purchases) and link it to online identifiers, often using household IP clustering which includes smart TVs and speakers.
Acxiom / Epsilon
Traditional brokers that have expanded into digital audience segments. They ingest hashed email addresses from smart device registrations to append behavioral data to their existing 3,000+ data points per U.S. consumer.
Samba TV
Specializes in smart TV data. Uses ACR to track what you watch, then sells this data to advertisers so they can retarget you on your mobile phone via "syncing".
The Platforms Themselves
Google, Amazon, and Meta technically don't "sell" your data to third-party brokers. Instead, they act as their own internal brokers, allowing advertisers to target you on their platforms based on the massive profiles they've built.
How The Exchange Happens
It operates through the Real-Time Bidding (RTB) system. When you load a webpage, an ad exchange broadcasts your device identifier and associated demographic tags (derived from cross-device tracking) to hundreds of advertisers simultaneously.
The advertisers have predefined algorithms that bid on impressions matching their target audience. If your profile indicates "high likelihood of purchasing pet food" (inferred from a voice assistant query linked to your IP), a pet food brand bids highest and wins the slot.
All of this happens in milliseconds.