The war of words over property portals continues apace after Rightmove’s record-breaking results this week.

The results came in ahead of all broker expectations and revealed a 75.5% profit margin, an 82% market share, and a growth in agent members of 2%.

In the Financial Times, Henry Mance writes: “Have estate agents shot themselves in the foot?

“Their launch of OnTheMarket was meant to break the cosy duopoly of Rightmove and Zoopla that dominates Britain’s market for online property ads. In fact it may inadvertently be turning a duopoly into a monopoly.”

Mance said: “[Rightmove] now has 50% more listings than Zoopla. Its shares, already at skyscraper heights, added a storey.

“There may be a lesson here about first-move advantage: Rightmove grew steadily, before Zoopla was assembled from a jumble of assets by Ferrari-driving entrepreneur Alex Chesterman.”

Mance adds: “More broadly, recent history suggests it is hard to topple an internet business based on network effects, by trying to offer virtually the same thing. Just ask Microsoft how its search engine Bing is getting on against Google.

“OnTheMarket says it can still overtake Zoopla and then out-compete Rightmove on price. But if estate agents want to tackle Rightmove’s pricing, they either have to offer something completely different (a Snapchat to Rightmove’s Facebook) — or wait for regulators to step in.

“Regulatory action, a distant prospect, becomes a tad more likely if Rightmove ends up a monopoly.

“Perhaps that is OnTheMarket’s real genius.”

Over to City A.M. which has Russell Quirk making, well, some rather predictable predictions.

OnTheMarket will “fizzle out” before its first birthday, he says, noting that it has “shouted from the rooftops” that in its first six months it has had 5m visits this month.

However, Quirk – whose own business, eMoov, is among the online agents banned from OTM – says OTM has failed to gain any meaningful inventory, while both Rightmove and Zoopla go from “strength to strength”.

Meanwhile, the analysts take their own view.

Fiona Cincottaa, of finspreads, said Rightmove’s figures suggest it “has not suffered the same fate as competition Zoopla, which in contrast has been negatively affected by the arrival of OnTheMarket”.

William Packer, of Exane BNP Paribas, said Rightmove is “gaining traffic share from Zoopla”.

He said that in its post-results briefing to City analysts, Rightmove estimated that net membership churn from Zoopla has stopped, but that it did not expect to see any “rapid return” of OTM agents.

And will Rightmove’s seemingly unstoppable quest to put yet more storeys on its skyscraper continue?

Yes, according to Packer.

Yesterday, he advised investors that there is “scope for Rightmove to expand their share of agent wallet”.