Researchers discovered that Amazon used voice data from its Echo devices to serve targeted ads on its own platforms and on the web. 

The finding contradicted Amazon's privacy policy, and resulted in calls for greater transparency on how the company collects, shares, and uses customer data.

By creating several personas to interact with Alexa and studying the results of their interactions with Amazon's Alexa virtual assistant, University of Washington, UC Davis, UC Irvine, and Northeastern University researchers concluded that Amazon and third parties collect users' data from their interactions with Alexa and share it with 41 advertising partners. 

The researchers also discovered that interactions with smart speakers generated far higher - up to 30 times - auction bids from advertisers than those without Amazon Echo speaker data.

Alexa users later filed lawsuits against Amazon for targeting them with ads using their personal voice recording interactions with Alexa without their consent, and that Amazon had been engaging in misleading and unfair conduct.