Stopping the recalculation of rows once data has been entered.

I have a stock tracking sheet that has one small issue.  Each week I enter new data (Stock price, dividends, new purchases, etc.)  This can change the calculated data in older entries.  I need to stop this recalculation.  It would be nice to have a command that can be put in that acts like this:  If today's date is older than previous dates, do not recalculate the old (row) data.

The old data should be "archived".  I could change the spreadsheet to have more sections if necessary.

Any assistance would be greatly appreciated.

Eric