Please note: this is not a grey import item, it’s a demo unit. It is an US market product and it comes with an US warranty. The seller says:
As one of the largest Sigma dealers in the USA we are happy to offer this great lens at a super price. It comes with the USA Warranty.
We had an in store demo and these were shown and put back in the box. Because of this we won’t sell them as new never opened
If you are buying on eBay, you may be interested to know that Canon is suing grey import retailers. Sigma 50mm f/1.4 DG HSM “Art” lens overview after the break.