The first thing I would suggest: learn how to use the LINEST() function to perform these regressions: http://office.microsoft.com/en-us/ex...in=HA010277524 Using the LINEST() function will allow you to perform the regression directly in the worksheet and eliminate the need to copy the equation from the chart to the spreadsheet.

Using the LINEST() function, you can either perform the regression in the source files and link that to this file or in this destination file, I'm not sure that it matters. I would probably also pull into this file the max(tenor) from each source file. From there, it should be easy enough to build a formula for Tenor and yield that will take into account the max tenor from the original source file.