The only stupid Question is the one you did not ask
If I understand you right you know that x will outperform y in a given period. The short answer is even if it goes up or down the way to make maney is to go with options contracts. Firstconsul and walstgolfer are the ones to comment on the technical aspects of how it works but basically by buying puts and calls or by writing puts and calls there is a way to gain money here. Try looking in the learning center under wallstgolfers post and I think he has an article that will explain it better than I ever could. The other thing to do is to read up on options basics on investopedia tutorial section. I hope that helps you out. If not keep asking
Joe