Network Rail failed to consider its tenants during the sale of arches across London.
That's the conclusion of an inquiry by the spending watchdog - the National Audit Office into the sell off.
It said the process had helped the firm balance its books, but had left businesses renting spaces, with no legal protection against rising costs from the new owner.
Those traders - many of which had been in sites for years - raised concerns at the time.
Network Rail has responded by saying its role is to run the railway, and that the sale had enable it to make improvements, while traders will benefit from investment from the new owner. The government said the rights of tenants were protected, and all agreements have been honoured.