New York, US: The spring art auctions began with a stumble on Tuesday when Sotheby's sale of Impressionist and modern art achieved less than two-thirds of its presale estimate.

While 80 percent of the 36 lots on offer found buyers, the evening's two main works - a Picasso portrait of his daughter Maya at age 2-1/2 and Giacometti's bronze "The cat" both went unsold.

Each had been estimated to fetch anywhere from US$16 million ($23.6 million) to US$24 million, and their failure left the meager US$61.37 million total well short of the US$81 million to US$118 million the auction house had hoped to bring in.

Art world eyes are trained on the two weeks of critical sales, the first to be assembled in New York since world financial markets fell into turmoil last autumn.

Sotheby's officials stressed that the sale, a much-scaled down affair from the $US350 million evenings that had typified the last several years, was actually among its more profitable in "quite awhile," in part due to the absence of guarantees, or prices promised to sellers regardless of whether a work sells or not.

But in a sign of the art market's drastic changes in just the last year, the sale's total was akin to the price paid for individual works sold at both Sotheby's and rival Christie's in recent seasons.

Earlier Tuesday, Standard & Poor's cut Sotheby's corporate credit rating to BB-minus from BBB-minus and said the outlook is negative, meaning it could downgrade again within 12 to 18 months.

It cited "a severe decline in company performance due to the greatly reduced art auction market," and projections that the market would remain down through 2009.

Sotheby's officials strained to find a positive note in the tepid auction result beyond its profitability.

"There are certainly buyers out there," said Simon Shaw, specialist in charge of the sale who noted strong prices for works by Monet, Pissarro and Renoir, all of which beat their high presale estimates.

Noting that 80 percent of the works were sold, Shaw said there was a "very positive message for the marketplace." But he added that the recalibration of the art market is very much an ongoing process.

The sale did achieve some strong prices, including its top lot, Piet Mondrian's "Composition in black and white, with double lines," which fetched US$9,266,500 including commission, or more than three times the low estimate.

Also noteworthy was a group of works by Tamara de Lempicka which were being sold by German designer Wolfgang Joop.

"Portrait of Marjorie Ferry" set a record for the artist, fetching US$4,898,500, while two more from the group were among the sale's top 10 prices.

The auctions continue on Wednesday with Christie's sale of Impressionist and modern art, which is estimated to take in about US$95 million, which might well be unrealistic given Tuesday night's results.