I'm trying to analyze a mechanical trading system I developed using Excel, but I'm beginning to think XL may not be the best program to use. The the size of the file is approaching 30mb and contains over 25 worksheets. This represents the long side trades only. I had to put the short trades into their own file to keep my computer from slowing to a crawl. The system is designed to scan a population of around 500 stocks and trade a basket of them with an approximately equal number of long and short positions. I'm currently testing the system over the last 5 years using daily OHLC data. My main problem, so far, is that I've just now finished all the necessary equations, but I'm only scanning the ten stocks I picked to test that the equations were correct and the file size is already over 60mb total. I realize that I may be asking a bit much from a celeron with 512mb of ram. So I'm running into both system resource limits and limits within XL. My version only has a max of 256 columns. Each worksheet will need to have a matrix of approximately 1400 days x 500 stocks. Am I using the wrong program to do the analysis? I like to actually see the data and work with it as opposed to having a program just spit out trading results for a set of parameters. What software do system traders use in order to develop and test strategies? Any suggestions would be greatly appreciated. Jeff.