The result is confusion for readers and frustration for professionals who know that the data is not contradictory so much as incomplete when taken in isolation.
The truth is straightforward: the UK’s headline house price indices are measuring different parts of the same market, at different stages of the transaction using different datasets and methodologies. None is wrong. Each is answering a different question. The main issue is timing.
Housing transactions unfold over months, not days. Asking prices move first, reflecting seller sentiment. Deals are then agreed; mortgages approved and only later do sales complete and get legally recorded. Each major index sits at a different point along that pipeline.
Rightmove – which last month reported the largest ever price increase seen in the month of January and the largest of any month since June 2015 – captures asking prices at the moment properties come to market. Zoopla, on the other hand, tracks prices at the point a deal is agreed, before completion.
Meanwhile Halifax and Nationwide measure mortgage approvals, reflecting what buyers are prepared – and able – to borrow.
Elsewhere HMRC’s Land Registry records completed transactions, often three to six months after the price was first negotiated.
So, what we have is asking prices leading the market while completed prices lag it.
And in fast-moving or turning markets that gap alone can explain why indices point in opposite directions in the same month.
There’s also a material difference in the data sources themselves.
Rightmove draws from estate agent listings and shows only advertised prices. It covers the vast majority of agents, making it an excellent gauge of sentiment and supply pressure but it does not tell us what homes actually sell for.
Zoopla sits closer to reality by focusing on agreed sale prices, blending agent data, historical transactions and valuation models. However, it still captures prices before renegotiations, fall-throughs or late-stage incentives.
Halifax and Nationwide rely solely on their own mortgage approval books. That makes their indices timely and methodologically consistent but also means that they exclude cash buyers and under-represent the prime and investor markets. Both are weighted towards first-time buyers and movers and while that in itself is informative it’s by no means comprehensive.
The Land Registry remains the most complete record of achieved prices. It includes cash buyers and legally completed transactions but it is backward-looking and subject to revision as late registrations feed through.
Then we have to consider geography and property mix which adds another layer of complexity.
Nationwide and Halifax have different regional footprints. Portal data from Rightmove and Zoopla can over-represent certain property types. Modelled indices smooth gaps that raw transaction data cannot. A strong month in regional family housing can lift a lender index while barely registering in London-heavy datasets, or vice versa.
Seasonal adjustment then further complicates matters. Halifax and Nationwide smooth their data to strip out predictable patterns while Rightmove publishes both adjusted and unadjusted figures.
The Land Registry revises data retrospectively. Short-term moves often look sharper in lender indices and noisier in portal data.
This is why asking which index is “most reliable” misses the point. Reliability depends on what you are trying to understand.
For accuracy on what actually happened then Land Registry remains the gold standard, albeit with a lag. For current direction and early warning signals the lender indices are invaluable. For sentiment and supply pressure, Rightmove is unmatched. Zoopla provides a useful bridge between intention and completion.
Professionals rarely rely on one dataset. Analysts, lenders and experienced journalists typically read several together: a lender index for monthly momentum, Rightmove for sentiment shifts and the Land Registry to confirm longer-term trends. When all three move in the same direction, the signal is strong. When they start to say different things, the market is usually in transition.
So why do headlines still appear to contradict each other? Because nuance is often compressed into a single number.
A rise in asking prices becomes “house prices up”. A fall in mortgage-backed purchases becomes “prices falling”. Seasonal effects, sample bias and month-on-month noise are stripped out in favour of drama.
At turning points, confusion peaks. Asking prices move first, completed prices lag and mortgage data sits somewhere in between.
And that’s when indices appear most divided. Not because the data is broken but because the market is changing direction.
The simple rule is this: contradictory house price headlines usually signal a market in flux, not one in chaos. Understanding where each index sits in the transaction pipeline matters far more than arguing over which one is right.
So while Rightmove reports that the average price of homes coming to the market for sale had risen in January to £368,031, a 2.8% increase from December (+£9,893) and the largest ever price increase seen in the month of January, and the largest of any month since June 2015… it’s worth pointing out that they are only back to where they were in the summer of 2025 and before any Budget rumours had started to circulate.
The information contained within was correct at the time of publication but is subject to change.
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