The apps on your Android smartphone not only track your movements and habits, they share what they know with over 20 companies apiece, a new study reveals.

Research by Oxford University, and reported in the Financial Times, reveals that nine out of 10 Android apps share your data with third parties. The app shares with a median of 10 third parties, and one in five apps shares information with over 20, the study found.

Researchers examined almost one million Android apps available through the Google Play Store in the US and UK – around a third of those available.

Information collected and shared by apps can include anything from age, gender, and location, to data on every other app on your phone.

By examining the code in apps, researchers were able to find not only how often data was shared, but also that it flowed ultimately to a handful of tech giants: Google’s parent, Alphabet, as well as Facebook, Twitter, Verizon, Microsoft and Amazon.

This data flows through a network of subsidiary companies before reaching the handful of parent companies.

The analysis showed that, as of the beginning of last year, 88% of apps could transfer information to companies owned by Alphabet, and 43% to firms whose parent is Facebook.

In the US, the Oxford researchers found, 90% of apps were able to share data, with 5% of those able to share with third-parties in China, and 3% to those in Russia.

The aggregation of this disparate data with such a concentration of businesses allows for extremely detailed profiling, the analysts say.

For example, if data from a dating app is shared with the same parent company as the producer of a banking app, it would be possible to establish the sexual preferences of a bank’s customers.

The authors say the extent of tracking differs greatly between categories of apps.

In particular, news apps, games, and those for children “appear to be amongst the worst in terms of the number of third-party trackers associated with them”, they noted.

Reuben Binns, the computer scientist who led the Oxford study, told the FT that most apps now rely on revenue from advertising.

“It feels like this legitimate business model has gone completely out of control and created a kind of chaotic industry that is not understood by the people who are most affected by it,” he said.

Google told the FT the research paper – which was peer reviewed – mischaracterised “ordinary functions”, such as an app sending feedback when it crashed, and its analytics.

Sourced from Oxford University, Financial Times; additional content by WARC staff