Millions of consumers with Barclays savings and current accounts will have "information about the transactions on your account" collected and shared as a result.
According to the Daily Telegraph, the bank is also planning to start tracking customers through their mobile phones or other "devices" - to help protect them from fraud - from October this year.
So if a payment is made in a certain country, for example, Barclays will "ping" the customer's mobile number to check the customer concerned is there.
This is all likely to sound worryingly like Big Brother to many Barclays customers. The high street bank is far from the only business to share more customer data, though.
Supermarket chain Tesco has been selling on the customer data gathered via its Clubcard loyalty card scheme, which has been running since the 1990s, to food and drink companies for many years.
And just days ago, mobile phone operators Vodafone, EE and O2 said they would start selling bundles of anonymised data on their customers to big advertisers to help them come up with targeted campaigns aimed at different age groups and demographics.
According to website The Drum, the bank said: "We only use information in a numerical, anonymised and aggregated way as is standard practice at many companies.
"Mobile location data will be used for fraud prevention purposes only and therefore only on the occasions where this is a transaction on a customer's account that has been picked up by our fraud detection systems."
Those who prefer not to have their mobile phones tracked can also choose to opt out of this new service.
However, anyone unhappy about their data being shared may prefer to start banking with a building society, which is less likely to sell customer information on to other companies.
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