I am writing an undergraduate disseration looking at performance pay and CEO incentives within the US oil and gas industry. i am looking at about 50 firms over a 5 year period. i need a measure for total shareholder wealth that is relatively easy to calculate (i've only got about 2 weeks), i can easily obtain data for (I have access to annual reports and proxy statements), and can be regressed on CEO compensation. if you could give me the formula for such a measure and instructions on where to find the data, that would be much appreciated.