Hi guys.

I am struggling with a problem and would appreciate any help.
Basically I want to make a system that can keep track of profit loss
on stock/bond transactions.I have made a userform where I input values
and choose whether a transaction is BUY or SELL. From here I want my
model to:

1. scan column A to see if a position in the respective paper already
exists by matching a value from the userform.

2. If a position exists a new "average price" should be calculated.
Say I already have a position in 1 bond which I purchased for 100. Now
I buy another bond at 110. The new average price should be 105 (100/2
+ 110/2) or (Average price/Total amount + new price/Total amount)

This value should then overwrite the existing "average price" value in
the same row in a column to the right.

Now if I later sell an amount say the 1 bound at 90. My total loss
will be -15 (90-105)*1 or (price - average price)*total amount. This
loss should be put into a "profit loss" column in the same row - and
pooled together with any other existing profit/loss.

Hope I have made my problem clear enough. Many thanks in advance.