The international art trade faced a crunch moment in Switzerland this week. Art Basel, the world’s biggest and most prestigious fair for dealers in modern and contemporary works, opened to V.I.P.s on Tuesday against a backdrop of declining auction sales and gloomy talk of a market downturn.

Sales were down 22 percent over last season at the latest May series of marquee modern and contemporary auctions at Sotheby’s, Christie’s and Phillips in New York. Christie’s is reeling from a ransomware attack and has cut back sales in London. Sotheby’s is reported to be in the process of laying off staff to cut costs.

“There’s a reset happening,” Wendy Cromwell, a New York- based art adviser, said in an interview at the Tuesday preview of Art Basel. “A lot of American collectors who were buying actively over the last 25 years are now aging out of the market. The Asian market has pulled back. And there’s a general sense of uneasiness about the world right now,” Cromwell added.

The Swiss fair, which opens to the public Thursday through Sunday, is the flagship event of the MCH Group, the Swiss owners of the Art Basel fairs, which include the slickly organized sister fairs in Miami, Hong Kong and Paris. (James Murdoch’s Lupa Systems investment firm is a major shareholder.) Dealers said this year’s 54th edition of Art Basel, featuring 285 galleries from 40 countries and territories, benefited from coinciding with the Venice Biennale. The presence of the fresh, Glastonbury festival-style Basel Social Club satellite fair on a farm on the outskirts of the city was also a plus.

Though Art Basel doesn’t release V.I.P. preview attendance figures, Magnus Resch, a New York-based art economist and author of the recently published book, “How to Collect Art,” said on Tuesday, “I can’t remember the attendance being higher in the first hour of the fair.”

Exhibiting dealers told him privately that business was not as good as two years ago, but “was not a disaster,” Resch added. “The mega-galleries won’t be hit so hard by what’s happening. The avenue of the stars is always crowded,” he said, referring to the aisle on the ground floor of the fair containing the booths of powerhouse international dealerships such as Gagosian, Hauser & Wirth, Pace, White Cube and David Zwirner.

Though Cromwell and other professionals noted a dearth of Americans at the fair, leading collectors such as the New York-based Steve Cohen and Donald and Mera Rubell from Miami were spotted in the crush.

“It has always been the gold standard for art fairs in my mind. It’s an opportunity to see what dealers consider to be the best examples of work by artists they represent,” said Meryl Rose, a Boston- and Miami-based collector, at the packed booth of Gagosian, where she had just bought “Lamy Ambuscade,” a gray-painted abstract steel sculpture from 2024 by the New York-based artist Carol Bove. Similar, but much larger Bove sculptures adorned the facade of the Metropolitan Museum in 2021. “It’s gutsy, strong and made by a woman. It’s so elegant,” Rose said of her purchase, which dealers said would have been priced between $600,000 and $800,000.

The top international dealers were noticeably playing safe at this year’s fair by offering classic contemporary works from the last 80 years, as well as more recent works by established names, like Bove. As usual, these galleries released lists of big-ticket sales at the end of the first preview day, though they were not quite as long as in previous years. At David Zwirner, a large and vibrant Joan Mitchell diptych, “Sunflowers,” dating from 1990-1991, sold for $20 million. Pace, in collaboration with the Paris dealership Galerie Lelong, sold three new editions of Jean Dubuffet’s monumental, playful 1970 painted bench sculpture, “Banc-Salon,” for 800,000 euros, or about $860,000, each. White Cube sold “Untitled 2,” a 1999 ink and polymer abstract by Julie Mehretu — currently the subject of a major show at the Palazzo Grassi in Venice — for $6.7 million.

“In spite of the ‘doom porn’ currently circulating in the art press and along gossip grapevines, we are very confident in the art market’s resilience and the first day of Art Basel has confirmed our perspective,” said Iwan Wirth, the co-founder and president of Hauser & Wirth, which has just opened a new branch in Basel, in a statement at the end of the preview. A rare, large “Untitled (Gray Drawing (Pastoral)),” from about 1946 by Arshile Gorky was the pick of his gallery’s multiple first day sales, priced at $16 million. Wirth did, however, concede in his statement that the market had returned to a “more humane pace.”

But a big-beast international gallery’s more humane pace can just mean “slower” for smaller dealerships. In recent years many collectors have headed straight for Art Basel’s less grand first-floor contemporary galleries specializing in works by young, emerging names that could rapidly rise in value at auction. Now that the resale prices for many artists are slumping, the first floor of the fair’s Galleries section was conspicuously less busy.

“Young artists are very expensive. You’re being asked to pay $20,000 or $30,000 for a work by an emerging name and you don’t know if you’ll ever get your money back,” Frederick Gordts, a Brussels-based collector, said. “You’re put on a waiting list, but young collectors don’t want to play that game any more. More and more are walking away.”

Still, collectors are always on the lookout for the next big, or at least biggish thing. “March, morning,” an enigmatic, bespoke-framed 2024 painting of a young boy on a flame red ground by the Berlin-based Scottish artist Oliver Osborne, for instance, drew plenty of attention at the booth of the Berlin and Los Angeles gallerist Tanya Leighton, before selling for 28,000 euros, or about $30,000.

Maike Cruse, the recently appointed director of Art Basel’s Swiss mother ship, said in an interview toward the end of the preview that the attendance and sales had “really exceeded our expectations,” but did not give any precise figures. Cruse, the former director of Gallery Weekend Berlin, said: “It’s a big relief,” but she added that “there’s less urgency in the market. People are nervous.”

Experts aren’t surprised that the dealer-based sector of the art market appears to be consolidating toward the bigger, “brand” galleries. “It is not only the new collectors attempting to go safe, but also the experienced ones,” said Marta Gnyp, a Berlin-based art adviser. “When times are uncertain, collectors prefer to avoid risks, financially and artistically. They would rather spend $20,000 or $30,000 with one of the Art Basel galleries than spend it with a smaller emerging dealership.”

These challenging market conditions didn’t seem to favor Liste, the nearby “discovery” fair that collectors have traditionally visited the day before Art Basel opens to V.I.P.s. The 29th edition, showcasing 91 international galleries, included the up-and-coming London dealer Archie Squire, exhibiting at his first art fair. Squire showed new kaleidoscopic photographs of crowded urban environments created using a cylindrical pin camera by the Frankfurt-based English artist Nina Porter. Resembling psychedelic microscope slides, five of these sold to European collectors for £3,000, or about $3,800, each, at Liste’s Monday preview.

“I felt it was quieter than I thought it would be by the end of the day,” said Squire, who has an unashamedly conceptual program.

There is still business being done at smaller contemporary galleries, it seems. As long as the prices are a lot smaller.