Sarah Krouse and Patience Haggin:

AT&T Inc. mines customers’ web-surfing habits as part of a broader advertising operation that taps into viewing data from television set-top boxes and location data from mobile phones, according to its privacy policy. Google Fiber gathers broadband-usage data on its customers.

Comcast Corp. and Charter Communications Inc. CHTR +1.34% say they have so far shied away from the practice, out of fear of alienating customers. Verizon Communications Inc. doesn’t use Fios internet-usage or cable-viewing data for targeted advertising, a spokeswoman said. Cable operator Altice USA Inc. says it has also stopped short of doing so, but retains flexibility to pursue the strategy if it chooses to later.