In theory, if SW is prospering, the companies they have LT contracts with should as well.

http://www.transworldnews.com/NewsStory.aspx?id=156010&cat=1

Silver Wheaton Corp. (USA) (NYSE:SLW) made a new 52-week high at $17.80 and now up 1.69% to $17.49. Silver Wheaton Corp. (Silver Wheaton) is engaged in the silver mining business. The Company has entered into nine long-term silver purchase agreements with Goldcorp (Luismin mines and Penasquito mine in Mexico), Lundin Mining (Zinkgruvan mine in Sweden), Glencore (Yauliyacu mine in Peru), Hellas Gold (Stratoni mine in Greece), Mercator (Mineral Park mine in Arizona, the United States), Farallon (Campo Morado mine in Mexico), Aurcana (La Negra mine in Mexico), and Alexco (Keno Hill property in Canada) whereby Silver Wheaton acquires silver production from the counterparties.