Real-Time Data

Just to update - the solution offered doesn't really solve my problem. The main reason is how the data comes into the sheet. The solution given would require a long list of every trade - known as time and sales. This would be a sheet that is incredibly long. Instead the price data is only in one cell - which is constantly updating. I want to create a list that adds a new line every 5 minutes. I think i can do that ok, but I need to get a high price value for the 5 minute period and a low value. That means I need to constantly monitor the one price cell and determine if it is higher than the previous value. I don't think that can be done in a spreadsheet as you get a circular reference.

Sorry - it is incredibly difficult to describe this problem.