Secondary Market

David Zwirner doubles down on competition with auction houses, launching online consignments portal

The new initiative marks an expansion of the gallery’s secondary market business

Banksynews

How Banksy is vying for control of resales as his market goes ape

Stunt suspicions swirl after Sotheby’s auction sees 2009 work by street artist sell for far more than its £2m high estimate

Art marketarchive

Auction sales of art shrank again in 2003

Figures show between 1.2% and 17% decline in turnover