The Financial Regulator is reportedly investigating claims of illegal collusion between mortgage brokers and estate agents.
Reports this morning say the regulator is probing allegations that some brokers may have revealed their clients' financial details to estate agents, enabling them to know how much buyers could afford to spend on a property.
This may have led to clients paying more for their house than would otherwise be the case.
This morning's reports say the regulator is particularly worried about the large number of smaller estate agents in rural towns who tend to also operate as mortgage brokers.