There are a lot of sites I can go to and get a chart of any stock such as finance.google.com, finance.yahoo.com, and others.
But I want to get a chart of how a portfolio consisting of multiple stocks would have performed. For instance, suppose I have a portfolio consisting of 100 shares of MSFT, 50 shares of GOOG, and short 100 shares of T. I would like to type in "100*MSFT + 50*GOOG - 100*T" in the stock ticker and have it show me the graph, but that doesn't work. Perhaps one of the existing services does have it and I just haven't figured out how to use it. For instance, some reading suggests that Google Finance will let me graph my portfolio, but I just don't see where, or if they are even really talking about what I want to do.