For example, app provider Slice Technologies Inc. lets users track the arrival of packages to their homes in its signature Slice app or block spam through another service it owns called Unroll.me without charge. But in exchange for those services, about four million users allow the company to read their emails. Slice, in turn, also analyzes receipts and other data in a person’s email which it packages into anonymized data for advertisers and hedge funds. It might show Amazon.com Inc. selling more of a particularly profitable item or an increase in Netflix subscriptions, which investors can use as a factor in their trades.

http://www.wsj.com/articles/wall-streets-insatiable-lust-data-data-data-1473719535