In most of the art market, one side of the table knows the real price and the other does not. Dealers, auction houses, and advisors sit on private records of what works actually sold for, who owns them, and what a seller will accept, and they price each deal against a buyer who can see almost none of that. Economists call this gap asymmetry, and it is the main reason the same painting can change hands twice in one day at very different prices. We think about it more plainly. For an investor weighing art against more transparent assets, this gap is the single biggest structural risk in the asset class, and a wave of price databases, valuation models, and disclosure rules is starting to close it.

It is worth being precise about why this matters. In public equities, every trade prints to a tape that anyone can read. Art has no tape. About two thirds of global art sales by value happen through channels that never publish a price, so the data you would use to judge whether you are overpaying mostly sits with the people selling to you. That is the problem we built a company to solve, so we will try to show our work on how big it actually is.

How much of the art market is private and unpriced?

Most of it. Global sales reached an estimated 59.6 billion dollars in 2025, a 4 percent gain after two down years, according to the Art Basel and UBS Art Market Report 2026 by Arts Economics. Of that total, dealer sales accounted for 34.8 billion dollars and public auctions for 20.7 billion dollars, with auction-house private sales just under 4.2 billion dollars.

The split matters more than the headline. Public auctions are the only segment that systematically reports prices. Everything sold through galleries, dealers, art fairs, and private treaty (an off-auction deal a house or dealer negotiates directly between two parties) clears at a price the public almost never sees. The 2024 figures from the prior-year report show the pattern plainly: dealer sales of 34.1 billion dollars plus auction-house private sales of 4.4 billion dollars came to roughly 38.5 billion dollars of the 57.5 billion dollar market, close to 67 percent, all transacted without a public price. Public auctions, the one transparent channel, were about a third of the market by value.

A note on the source. Arts Economics is explicit that even its own totals are estimates built from surveys and partial reporting, and not a full transaction record. The market is also one of the few large global markets with no mandatory price reporting and, in the United States, no dedicated financial regulator. When we started, this is the gap that struck us as the real inefficiency. Half of the market trades at public auction, which is more visibility than people assume, and Sotheby's has been around for 275 years. The other half is private, and when most prices are private and nobody is required to disclose them, the participant who keeps the records holds the advantage. That is the structure. Now look at how people monetize it.

How do dealers and advisors profit from private price information?

The most direct way to profit from an information gap is the undisclosed markup. A dealer or advisor quietly buys a work, or secures control of it, at one price, then resells it to a client at a much higher price without revealing the spread or the fact that they own it.

The reference case is the dispute between Swiss dealer Yves Bouvier and Russian billionaire Dmitry Rybolovlev, whose litigation stretched into 2024 and which the art trade still treats as the standard example. In the most scrutinized transaction, Leonardo da Vinci's Salvator Mundi sold in a Sotheby's-brokered private sale in May 2013 for roughly 75 to 80 million dollars to an undisclosed buyer, Bouvier, who resold it the same day to Rybolovlev for 127.5 million dollars. That is a markup of about 44.5 to 52.5 million dollars on one painting, captured because the buyer never learned the real purchase price or that his supposed agent was acting as the seller. [NEEDS UPDATED DATA: the transaction itself is from 2013, cited here as a teaching case; a comparable post-2024 undisclosed-markup case with disclosed figures would be stronger]

This is a fiduciary problem, and it is misunderstood in the art market. In New York, if we sell you a 30 million dollar painting we bought for 15 and we are secretly making 10 on the side, we have an obligation to tell you, you find out, and you almost always win that lawsuit, because the laws are clear. The art trade often just does not operate understanding those laws. Smaller versions of the same edge run constantly through the advisory layer. Advisors who present themselves as independent often collect introductory commissions, payments for connecting a buyer and seller, from the gallery or auction house on the other side of the deal. Artsy reported that these undisclosed fees taint the advice a collector gets, because an advisor steering a client toward a specific house may be doing it to collect a hidden commission rather than because it serves the client. The advisor knows both the seller's floor and the buyer's ceiling. The client knows neither, and so pays the spread.

Gallery pricing compounds the problem. Many galleries do not post prices, which lets them quote different numbers to different buyers and anchor the figure to a collector's perceived wealth rather than to any stable market level. Without a public reference price, the buyer has no way to check the quote. The whole edge depends on the buyer having nowhere to look.

Are auction prices an honest reflection of demand?

Mostly, but the visible price is not always the real one. Public auctions look transparent because a hammer price gets announced and reported. The mechanics underneath are less open, and an investor should understand them before treating a result as a clean signal.

Chandelier bidding is legal in many jurisdictions. The auctioneer calls out fictitious bids, off the wall or off the chandelier, to lift bidding up toward the seller's reserve (the confidential minimum the seller will accept). Only the house knows the reserve and the exact point where imaginary bids stop and real ones begin. A bidder in the room cannot easily tell whether they are competing against a rival or against the auctioneer's price ladder, which can push a hesitant buyer higher than they would otherwise go.

Guarantees bend the headline price further. A third-party guarantee, often called an irrevocable bid, is an arrangement where an outside party commits before the sale to buy a lot at a set price if bidding falls short. In exchange, if the work sells above that level, the guarantor usually takes a cut of the upside. The public sees the gross hammer price. It does not see that the guarantor's net cost, after the rebate, is lower, and it does not learn the guarantor's identity or the size of the guarantee. The guarantor, meanwhile, has seen the house's internal estimates and condition reports and can bid with far better information than anyone else in the room.

This is common at the top of the market. Of the high-value lots tracked in 2025, about 78.3 percent of guaranteed-segment value was committed before the sale, roughly 1.93 billion dollars guaranteed against 0.53 billion dollars not guaranteed. Overstone Art Services counted 137 third-party-guaranteed lots in the November 2024 New York and London sales, at an average realized price near 3 million dollars. When a large share of marquee lots is pre-sold to insiders who know the economics, the reported hammer overstates how much genuine competition set the price.

We want to be careful here, because we use auction data heavily and we think it is the best public data the market has. The mechanics above are reasons to read a single hammer price with discipline, and they are also exactly why a methodology matters more than any one result. We will come back to that.

Why does hidden provenance create the most risk for buyers?

Because price is only half the asymmetry. The other half is provenance, the documented ownership history of a work, which carries the risk that matters most: authenticity and clear title.

Catalogues routinely list a work's history as nothing more than "Private collection." That is tolerated, and it hides exactly the facts a buyer needs. The Knoedler gallery case, in which a long-established New York dealer sold tens of millions of dollars of forged Abstract Expressionist paintings, turned on this point. Courts later flagged undisclosed ownership history and concealed negative information as the central red flags, since a seller who knows about gaps or doubts and stays silent may cross from discretion into fraud.

The edge comes from selective silence. A dealer may know about a prior failed sale, a negative opinion from a scholar, or a past restitution claim, and disclose none of it. Because the supporting records and expert correspondence are private, the buyer usually cannot find the gaps on their own. The work sells for more than full disclosure would allow, and the hidden risk transfers to the buyer along with the painting. That is the asymmetry at its most expensive.

Is the art market becoming more transparent?

Slowly, and it is coming from three directions at once. For most of the market's history, the only people with the data were the people selling. That is changing, though unevenly.

Price databases have built a public record where none existed. The Artnet Price Database now holds more than 19 million auction results going back to 1985, and rivals such as Artprice, MutualArt, and LiveArt aggregate auction history, artist-level price trends, and market indices. None of these can see private dealer sales, so they cover only the transparent third of the market. Within that third, they let a buyer pull comparable sales an advisor would once have summarized selectively, which makes a cherry-picked "comp" much harder to pass off. We took this further for our own purposes. There was no reliable index methodology when we started, so we hired interns, bought thousands of paper auction catalogs, and recorded individual purchase-and-sale events to build one. The point of all that work is that the data is knowable. It is just expensive to assemble.

Artificial intelligence and sentiment research add a second layer. ArtTactic and similar firms turn auction data and collector surveys into market-direction and artist-risk signals, and AI valuation tools estimate fair value from comparables, medium, size, and an artist's career stage in seconds rather than weeks, which compresses the research advantage full-time insiders held over occasional buyers. Blockchain provenance registries attack the ownership-history gap directly by recording title and exhibition records in a tamper-resistant ledger, though adoption is still early and far from universal.

Regulation is the third force, and it is moving fastest in Europe. The EU's Fifth Anti-Money Laundering Directive has treated dealers and auction houses as obliged entities since 2020, requiring customer due diligence, source-of-funds checks, and recordkeeping on transactions above 10,000 euros, with parallel rules in the UK. The United States still has no mandatory anti-money-laundering supervision for art dealers, but the bipartisan Art Market Integrity Act, introduced in the Senate in July 2025, would extend Bank Secrecy Act obligations to most art market participants on sales of 10,000 dollars or more. To be clear, the money-laundering risk in art is often overstated in the popular press, because KYC rules already make it very hard to launder money through art. The more useful effect of these rules is that they attach identities to transactions. None of them forces price disclosure, which is the asymmetry that hits investors hardest. They chip at opacity, and they signal that the era of treating the art trade as a fully private club is ending.

The Bottom Line

  • Roughly two thirds of global art sales by value, about 38.5 billion dollars of a 57.5 billion dollar market in 2024, move through dealer and private-sale channels that never publish a price, which means most of the data needed to judge value sits with the seller.
  • The clearest way participants profit from that gap is the undisclosed markup, shown at its extreme when Salvator Mundi was resold the same day in May 2013 for a 44.5 to 52.5 million dollar gain because the buyer never saw the real purchase price.
  • Auction prices look transparent but are shaped by chandelier bidding and pre-arranged guarantees; about 78.3 percent of guaranteed-segment value at the top of the market in 2025 was committed before the sale, so the reported hammer overstates genuine competition.
  • Selective nondisclosure of provenance lets sellers hide authenticity and title risk, the failure at the center of the Knoedler forgery case, and transfer that risk to buyers at a full price.
  • Price databases such as Artnet, now holding more than 19 million records, along with AI valuation tools and blockchain provenance registries, are shrinking the research edge, but only within the transparent third of the market.
  • Anti-money-laundering rules in the EU and UK and the proposed US Art Market Integrity Act are attaching identities to deals, yet none of them mandate price disclosure, so the core investor-facing asymmetry remains largely intact.

Sources

  1. Arts Economics. "The Art Basel and UBS Global Art Market Report 2026." Art Basel and UBS, March 2026. https://www.artbasel.com/stories/the-art-basel-and-ubs-global-art-market-report-2026?lang=en
  2. Arts Economics. "The Art Basel and UBS Art Market Report 2025: Global Market." Art Basel and UBS, 2025. https://theartmarket.artbasel.com/the-art-market-2025/global-market
  3. Halperin, Julia, and others. "The Secret Brokers of High-End Art Deals." Artsy, updated 2025. https://www.artsy.net/article/artsy-editorial-secret-brokers-high-end-art-deals
  4. Courthouse News Service. "Sotheby's Messy Price-Gouging Dispute Heads to Jury Deliberations." Courthouse News, January 2024. https://www.courthousenews.com/sothebys-messy-price-gouging-dispute-heads-to-jury-deliberations/
  5. The Art Newspaper. "Seven Red Flags in the Knoedler Trial That Should Give Dealers and Sellers Sleepless Nights." The Art Newspaper, updated 2025. https://www.theartnewspaper.com/2016/10/27/seven-red-flags-in-the-knoedler-trial-that-should-give-dealers-and-sellers-sleepless-nights
  6. Grossman LLP. "New York Times Draws Attention to (Lack of) Art Market Oversight." Grossman LLP, updated 2025. https://www.grossmanllp.com/New-York-Times-Draws-Attention-to-Lack-of-Art-Market-Oversight
  7. Overstone Art Services. "Auction Guarantees in Transition: Adapting to Market Shifts and Collector Interests." Overstone Art Services, February 2025. https://www.overstoneart.com/press-content/auction-guarantees-in-transition
  8. Artnet. "Artnet Price Database." Artnet, 2025. https://www.artnet.com/price-database/
  9. American Society of Appraisers. "ASA Partners with Artnet to Offer Exclusive Discounted Access to the Artnet Price Database for ASA Appraisers." ASA Newsroom, December 2025. https://www.appraisers.org/asa-newsroom/article/2025/12/04/asa-partners-with-artnet-to-offer-exclusive-discounted-access-to-the-artnet-price-database-for-asa-appraisers
  10. DLA Piper. "Art Market Integrity Act Introduced with Bipartisan Support to Combat Money Laundering Risks in the Art Industry." DLA Piper Insights, August 2025. https://www.dlapiper.com/en/insights/publications/2025/08/art-market-integrity-act-introduced-with-bipartisan-support
  11. MyArtBroker. "The Art Market Is More Regulated Than You Think." MyArtBroker, January 2026. https://www.myartbroker.com/investing/articles/art-market-regulations
  12. Observer. "The Art Market Enters 2026 With Confidence and a Sharp K-Shape." Observer, January 2026. https://observer.com/2026/01/art-market-outlook-2026-arttactic-survey/