More banks are likely to follow Halifax in outsourcing their credit card processing.
This week's deal between the former building society and services house EDS could reach £100 million over 10 years.
Robert Morgan, chief executive of outsourcing consultant Morgan Chambers, said it will open the door to further agreements, despite the financial sector's dislike of such deals.
"Financial services people have a mentality of guarding their data closely," said Morgan. "But ecommerce is bringing huge pressure to bear on them."
Some banks have already dismissed such deals.
James Donehey, chief information officer of US credit card firm Capitalone, said last month that releasing core information is a "fundamental mistake". Capitalone spent millions to escape a contract between its former owner and EDS.
In the UK, however, EDS is preparing credit card capacity well beyond what is needed by Halifax, which issues only 2.7 per cent of the UK's credit cards. EDS also handles cards for Girobank and HFC, which runs Goldfish.
EDS said that payments would be based partly on volumes of business.
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