IN PLAIN ENGLISH
What you actually paid for the shares you still own. When you sell part of a position, the cost of those sold shares is removed so the figure only reflects what's still in your portfolio.
FULL DEFINITION
The remaining cost basis of the shares you currently hold, after removing the cost basis of shares you have sold.
EXAMPLE
You bought 100 shares for £1,000 (£10 average) and later sold 40. Sold cost basis = 40 × £10 = £400. Total Cost = £1,000 − £400 = £600.
HOW IT'S CALCULATED
For each holding: total buy cost − (shares sold × average cost per share), where average cost per share = total buy cost ÷ total shares bought. Each buy's cost is entered in the stock's own trading currency and converted into your portfolio currency at the exchange rate on its purchase date, so later FX moves do not change what it cost; a buy whose purchase-date rate was unavailable is converted at today's rate until the holding is next saved. Holding costs are then summed.
Educational content only. It is not personal financial advice.