2011 sales at Sotheby's, Christie's

The art market will undergo a major strength test during the next two weeks as London's chief auction houses hold their summer sales of Impressionist, modern and contemporary art. They may also be waiting to see if recent signs of weakness in stocks and the overall economy will have an effect.


One group isn't slowing down: sellers. During the recession, collectors who weren't desperate for cash held onto their art trophies, which resulted in thin auction catalogs and fevered bidding over the few masterpieces on offer. But now confidence (and catalog thickness) is increasing. Christie's Tuesday evening sale contains 92 pieces, up from a typical 50. The offerings include artists who aren't exactly household names, like Belarusian sculptor Ossip Zadkine and Belgian neo-Impressionist Théo van Rysselberghe.

The latest roster of sellers includes Christian Duerckheim-Ketelhodt, a German industrialist selling nearly 60 pieces of postwar art—including Sigmar Polke's 1967 "Jungle"—at Sotheby's for at least $53 million combined. Kay Saatchi, the ex-wife of British ad executive Charles Saatchi, is also selling off 31 pieces of contemporary art at Christie's.

Elsewhere in these sales, the University of Sydney is offering its 1935 Pablo Picasso, "Young Girl Sleeping," for at least $14.6 million at Christie's. The school says it plans to put any proceeds into scientific research. New York's Museum of Modern Art is joining in with its Jean Arp globby gold sculpture from 1957, "Evocation of a Human Form, Lunar Spectral," for at least $1.3 million at Sotheby's. The museum says it will use the funds to buy more art.

Despite all the discretionary selling, art-market experts say the real juggernaut of these sales will likely be the estate of Ernst Beyeler, a Swiss dealer who co-founded the Art Basel fair in 1970 and later created a private museum for his collection in Riehen. On Tuesday, Christie's will begin selling off 110 pieces Mr. Beyeler kept at home or in his gallery, led by Claude Monet's "Water Lilies," a 1914-17 work that's priced to sell for at least $26 million. Other Beyeler pieces include Picasso's "Bust of Françoise," priced to sell for at least $11 million.

A DETAIL FROM Claude Monet's 1914-17 'Water Lilies'

The star of the Sotheby's Wednesday sale of Impressionist and modern art is Egon Schiele's "Houses With Laundry (Suburb II)," a 1914 painting expected to go for at least $35.6 million. Vienna's Leopold Museum is selling the work so that it can make restitution to the heirs of a Jewish dealer. His collection was confiscated by the Nazis and wound up in museums like the Leopold.

Sotheby's : A detail from Egon Schiele's 1914 'Houses With Laundry (Suburb II)'