Data-gathering firms and technology companies are aggressively matching people’s TV-viewing behavior with other personal data — in some cases, prescription-drug records obtained from insurers — and using it to help advertisers buy ads targeted to shows watched by certain kinds of people.

At the same time, cable and satellite companies are testing and deploying new systems designed to show households highly targeted ads. The goal: Emulate the sophisticated tracking widely used on people’s personal computers with new technology that reaches the living room. Get the full story »