Financial analysts have been querying the negative effects of real estate agents boycotting Trade Me and now the Commerce Commission has begun a probe.
Gordon Irving, commission spokesman, said the real estate ad situation was of interest to the organisation.
"I can confirm that the commission is investigating this issue. It is too early to determine the possible outcome of the investigation," he said.
Analysts have raised the issue, saying real estate is a major source of revenue for Trade Me so any change would negatively affect the business.
The NZ Herald has previously reported a group of real estate agents said they would boycott Trade Me after the company announced price rises.