What Actually Counts as a Real Estate Comp in NYC Sales

A signed deed in New York City typically takes one to two weeks to reach the public record, and the lag can stretch to several months during a filing backlog. That gap alone means the comparable sales, or comps, an agent pulls on a Tuesday afternoon are already missing whatever closed most recently, and in a building where a difference of ten floors can move a price by tens of thousands of dollars, a comp that is slightly wrong is not a rounding error.

A comp is a closed sale of a similar apartment, used as the evidence for what a similar unit is actually worth right now, not what a seller hopes it is worth. I run my own data pipeline on listing data rather than outsourcing the pull, so the cross-checking is fast enough to leave time for the judgment calls a spreadsheet cannot make. Below: what makes a comp valid in New York City, where the sale data lives, and where a comp you found yourself is likely to mislead you.

A Comp Is a Sale, Not an Opinion

A true comp has three non-negotiable qualities: it closed, it is recent, and it is genuinely similar in structure to the subject apartment. A listing that is still active does not qualify on its own, because an asking price is a request, not a result. An "in contract" listing is closer but still not final, since financing contingencies and attorney review can still change the number before closing. Only a recorded closed sale tells you what a buyer and seller actually agreed a specific unit was worth.

Similarity means more than bedroom count and square footage. A one-bedroom on a high floor with a renovated kitchen and a two-bedroom cut down from a larger layout on a low floor can carry the same listed square footage and still be worlds apart in what a buyer will pay. Every reliable comp analysis starts by throwing out anything that does not share the property type.

Why Same-Building and Same-Line Sales Carry the Most Weight

Many New York apartment buildings repeat a floor plan, so the same layout stacks on every floor in a column called a line. A sale of "the 6 line" three floors down from the subject unit is often the single best comp available, because it removes almost every variable except floor height, light, condition, and whatever renovation work has been done since the last sale.

Appraisers lean on this too. Lender guidelines for condominium appraisals call for at least one settled comparable sale from within the subject building or project when one exists, because a same-building sale controls for the building's financials, amenities, and location in a way that a comp three blocks away cannot. When I price a listing, I start with the building's own sales history. For how appraisers weigh the building against the wider market, see my NYC home appraisal guide.

When no same-line sale exists, the next best comp is a different line in the same building, then a comparable building on the same block or in the immediate radius with matching construction era, unit count, and amenity package. The further a comp has to travel from the subject building to find a match, the more adjustment work it needs and the less confidence it deserves.

The Adjustment Math Nobody Puts on the Listing Sheet

Every difference between the comp and the subject apartment gets translated into a dollar adjustment, added or subtracted from the comp's sale price to estimate what the subject apartment would have sold for under the same conditions. The categories that matter most in a New York City apartment are floor height, light and exposure, renovation level, outdoor space, and how much time has passed since the comp closed in a market that is moving.

The table below is an illustrative example built from made-up numbers to show the arithmetic. It is not a real transaction or typical pricing for any building.

The kitchen and the balcony pulled the number in opposite directions, and the net adjustment came to almost 3% of the sale price. Run three or four comps through the same process and average the adjusted values, and you have something more defensible than any single unadjusted sale price.

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Where the Sale Prices Actually Live: ACRIS and the Co-op Gap

Condo sales in New York City get recorded as deeds with the New York City Department of Finance, searchable free through ACRIS, the city's Automated City Register Information System. That record includes the recorded sale price, but it is not instant. A signed deed generally takes one to two weeks after an attorney files it to show up in ACRIS, and delays of several weeks to a few months are common enough that treating a "no recent sales" search result as proof nothing has closed is a mistake.

Co-op sales work differently. A co-op share is personal property, not real property, so a co-op sale does not get recorded as a deed at all. There is no ACRIS deed to search for a co-op closing. If the buyer financed the purchase with a loan, a UCC-1 financing statement gets filed against the shares and is recorded through ACRIS, showing the lender and the loan amount. That is a partial data point at best, since it reveals what was borrowed, not the full purchase price, and an all-cash co-op sale leaves no public financing record at all. Agents fill that gap with building-level sales history, portal listings, and relationships with other brokers who track what actually closed in a given line.

Why Your Agent's Comps and an Appraiser's Comps Can Disagree

A seller can hear one number from an agent and a lower one from the bank's appraiser weeks later, because the two are not doing the same job with the same rules.

An agent's comp selection is built to answer "what will this apartment sell for," while an appraiser's comp selection is built to answer "what will a lender's collateral support," under a stricter and more conservative recency and settlement standard. When the two numbers diverge by more than a small margin, the gap is usually explained by one side including a comp the other side is not allowed to use. My appraisal guide covers what to do when that gap threatens a closing.

When a Comp Is Too Old to Use

A comp does not expire on a fixed calendar, but its reliability decays as the market moves. A sale from eight months ago in a market that has since shifted describes a market that no longer exists. Lenders acknowledge this too: a settled sale within roughly the last 90 days is preferred when one is available, though an older sale can still be used if it is the best evidence on hand and the reasoning is documented.

The practical fix is the time-of-sale adjustment shown in the worked table above, treating market movement since the comp closed as its own line item rather than ignoring it. In a fast-moving market, a 6-month-old comp without a time adjustment is not conservative. It is stale.

What a Portal Shows vs. What Actually Closed

Public listing portals are a starting point for research, not a finished comp analysis. StreetEasy publishes closed sale prices on unit pages and in building sales histories, and that is the closest thing the public has to a free NYC comp set alongside ACRIS. A few gaps matter in New York City specifically. Portal data usually lags the true closing by the same weeks it takes a deed to reach ACRIS, so the most recent closings are often missing entirely. Some portals also carry a listing's original ask alongside a final sale price without making clear how many price reductions happened in between, which flattens a negotiation into a single misleading number. And a meaningful share of NYC sales activity, particularly among co-ops and off-market deals, never appears on a public portal at all.

A portal search is a first pass, not a final answer. Reading a building's full sales history, cross-checking ACRIS filings, and accounting for off-market closings separate a genuine comp analysis from a number pulled off a search results page. If you are trying to price a home for sale rather than research the mechanics of comps, my pricing strategy guide and my apartment valuation guide walk through that process in full. Once you have a defensible number, the seller net proceeds calculator turns it into what you would actually take home, and the capital gains guide for NYC sellers covers what part of the gain is taxable. If you would rather have the comps run for you, that is what a seller consultation starts with.