Guy and Myriam Ullens, among the world’s biggest owners of Chinese contemporary art, said they will sell part of their collection to fund their namesake private museum in Beijing and buy more artworks.

The couple assigned Poly International Auction Co. to sell three Chinese contemporary art pieces and several antiques, the Ullens said yesterday in an e-mail response to Bloomberg News’s query, declining to give specifics. The items will be sold at a Poly auction in May.

Demand for Chinese contemporary art dropped in the second half of 2008, as the latest bout of credit crisis slowed buying at Hong Kong and Beijing auctions. There isn’t a price index for the art category; anecdotal auction results in major markets like Hong Kong and large transactions at galleries serve as the best indicators for where prices are headed.

We have always “dynamically managed our collection,” the Ullens said in the e-mail.

Chinese contemporary art prices may drop further in the next six months as the economic slump continues, according to a survey this week by research company ArtTactic Ltd. This category is broadly defined as works produced since the 1960s.

The couple bought 15 pieces of Chinese contemporary art last year, including an Ai Weiwei chandelier for $657,000 from Sotheby’s sale of Asian art in New York. They also bought He An’s neon-light characters, using them as signage in their Super Ganbei cafe at the Ullens Center for Contemporary Art in Beijing.

Belgian Family

Guy Ullens, 74, is the scion of a Belgian family of diplomats and industrialists. His father, Jean, was a diplomatic staff in China, while uncle Baron Jules Guillaume was Belgium’s ambassador to China from 1931 to 1937.

Guy Ullens’s collection began with Chinese classical scroll paintings of the Song, Yuan, Ming and Qing dynasties. In 1985, he traveled frequently to China to run the family’s sugar business and became interested in contemporary art.

His family-owned Artal Group in 1999 paid $735 million for a controlling stake in Weight Watchers International Inc., the world’s biggest chain of diet centers.

The Guy & Myriam Ullens Foundation owns about 1,500 paintings, sculptures, installations and video works in its collection. They opened the Ullens Center for Contemporary Art in November 2007 in Beijing’s 798 art district, housing their collection in a Bauhaus-style former arms factory.

The UCCA is the largest non-profit exhibition space at 798, funded by philanthropists, sales from the museum’s gift shop and its Super Ganbei cafe.

In July 2008, the couple displayed more than 90 pieces of work by 60 Chinese artists in their “Our Future” exhibition. The collection included paintings by Zhang Xiaogang, Zeng Fanzhi, Wang Guangyi, and the late Chen Yifei, as well as installations by Wang Du.