Aggregator-Blocking Service May Be Blocked by Bad Timing

A new service meant to foil account aggregators by prohibiting them from taking customer information from bank Web sites is threatening to crack a delicate peace forged in recent months between scrapers of customer data and their targets.

Vyou Inc. of San Jose, Calif., has rolled out Aggregation Control Services, which lets institutions manage third-party Web access to customer information. The service can identify the agents or “bots” that aggregators use to gather data from Web sites and allow only certain ones to go through — or it can block access altogether.