OnTheMarket claims monthly visits to its website hit a record 25.4m in May - but the portal’s latest update gives no details on agency membership.
The portal says its May visits show an eight per cent increase on January's seasonal high and previous record month of 23.5m visits.
A statement this morning says the increase in traffic helped to deliver record leads for its customers, and the last month the portal generated a 15 per cent increase in phone and email leads compared with January.
In terms of inventory OTM says it has, as of earlier this week, over 650,000 UK residential listings - that's over 83 per cent of Zoopla's and approximately 65 per cent of Rightmove’s.
Meanwhile the number of instant property alert emails sent by OnTheMarket during May reached in excess of 100 million.
However, this morning's statement to shareholders and the City makes no mention of agent numbers, nor details of those switching from free or discounted membership deals to market-rate deals - a key performance indicator in OTM's goal of displacing existing portals.
In April OnTheMarket released shares to agents signing long term deals with the portal, seen as evidence that some customers had become market-rate customers.
Ian Springett, OTM's chief executive officer, says in this morning's statement: "Our May performance is further evidence that our growth strategy is working. We have delivered another set of record-breaking traffic and leads results for our estate and letting agent customers, many of whom are choosing to list their properties on a 'New & exclusive' basis. This is driving traffic to our portal while injecting competition into a market which was previously a 'duopoly'.
"The high volume of instant alert emails now being sent each month shows how our engagement with active property-seekers and the value we deliver to agents are both continuing to grow strongly."
OTM releases annual trading figures next week.