OK - so I'm probably being stupid but I've just realised that the information showing in my Portfolios has been misleading me and as this has presumably been happening for years, I'm not very happy. Whether that should be with myself or with stocko, I'm not sure.
I now know that I should have been aware that stocko operates a "first in, first out" methodology and, to me that seems OK for a "trader" but not so good for an investor who might take time to build up a holding in a share, hopefully buying more as the "story" unfolds, selling a bit when I feel the SP has got ahead of itself or it's percentage of the portflio has become too large and buying more when the SP dips.
But, assuming that the share price basically goes up over time those sales later on don't reduce the "cost" of the overall holding by the value of the sale but rather reduce the cost by their value at the earliest cost price (hope that makes sense and hope that I understand what happens correctly).
So, for me, the "Cost", "Gain £" and "Gain %" figures are now meaningless.
It now seems that the only way to get the figures to accuratly reflect the performance of my investment in a share over a number of years is, after buying or selling, to delete the "Holding" from the portfolio then add the share again with the total number of shares held and the running total of what that holding has cost me after allowing for value of any sales along the way.
Or am I doing it all wrong and (a) there's a better way to keep track or (b) I'm wanting to do things the "wrong" way and really the stocko method is the correct and best way to monitor share holdings and their performance.
Of course, none of the above applies if I just buy a holding once and then don't sell any.
Any help much appreciated - I've been doing this a long time but still keen to learn.
I believe it is normal practice to show the purchase cost as the AVERAGE, so sum the total purchase costs and divide by the number of shares held.
Sales make no difference to the average cost of the holding, since once sold, the share sold are no longer part of the holding.
As I see it, calculating the average cost in this way is both logical and convenient for any capital gains planning.
Also, when evaluating the remaining holding, confusing the issue by considering what profit has already been made on the trade goes against an awful lot of theory on investing.
