The art market, which has enjoyed a robust six-year boom in prices, faces a big test over the next two weeks as it finally shows signs of faltering amid the global financial crisis.

Christie’s and Sotheby’s, the two main auction houses, expect to sell up to $1.7bn in artworks in New York’s two-week sale season which begins on Monday and which has traditionally been a key barometer of fine art prices, setting the tone for the coming months.