Macro assistance required please
 

Would anyone be able to assist with code to do the
following.

I use my spreadsheet to monitor movements in some personal
Stock prices each day.
My spreadsheet links to a web site containing prices and
by clicking a button called Update on my sheet, I can
refresh these prices. These prices are then automatically
entered in my sheet in a range allocated for the purpose
which is CA3:CB26. Column CA contains the Stock Code and
CB the price.

I may click on the update several times a day up to a
maximum of about 20 times. Say 20.

I'm trying to get a handle on the average movement or
trend of the individual prices up or down and the
percentage of that movement from the first time I click
Update for that day. So, for example, Stock number2 which
I may have updated say 5 times that day will show me that
the average trend (or movement) is Up by x% or Down by y%
from the first update. Same applies to all the other
stocks as the Update button does all of them at once. I
don't know if trend is the appropriate word or average is
a more accurate definition.

I have an area on my sheet where I can allocate 20 entries
which is CG3:CZ26. The first Update would put the opening
prices in CG3:CG26.

I had a go using this range, but only succeeded in getting
totally confused and the whole thing developed into a
monster.

Macro code would be a far better alternative but I'm lost
at this point.
If I've explained my need without confusing the issue,
could anyone help me solve this problem.

Thankyou for any assistance.