If I create a Balance Sheet, stock values are calculated incorrectly.

For example,

If I buy 300 shares of XYZ at $20.00, the asset value will be reported
(correctly) as $6000.00.

If the price of XYZ is later updated to $35.00, the asset value is still
reported at $6000.00. I think the reported asset value should track the price
of the stock.

If I then sell 100 shares of XYZ at $40.00, the report shows the value of my
XYZ holdings as $2000.00 (which seems to come from the initial investment, minus
the proceeds of the sale, or $6000.00 - $4000.00). It should be the product of
the remaining number of shares (200) and the price per share ($40.00), or $8000.00.

If I sell another 50 shares at $40.00, the asset value goes to zero ($6000 - $4000 - $2000), even though I still have 150 shares which are worth $40 per
share.

If I sell another 100 shares at $50.00, the report shows a value of $5000, which
is the sum of the proceeds of the three sales ($4000 + $2000 + $5000) minus the
original cost ($6000).

In other words, the calculated value of my asset seems to be

   abs( (sum of investments) - (sum of proceeds of sale) )

which is a meaningless number.

Oddly enough, when I do sell all of my remaining shares, the asset value then
goes to zero, abandoning the above formula.