Sigma USA has announced its 18-35mm F1.8 DC HSM Art lens for APS-C DSLRs - the world's first constant F1.8 zoom - will be available from July at a street price of around $799.

http://www.dpreview.com/news/2013/06/14/Sigma-gives-price-and-availability-for-18-35mm-f1p8-DC-HSM