I have two ETF’s that basically track the ASX200 and ASX300 ie. A200 and VAS. Every now and then I purchase more of them or sell some. So I have multiple parcels of them with various purchase prices.
For the sake of explaining this error I will simplify the reality here so it makes the error more obvious. When it comes to capital gains tax calculations assuming I decided to use FIFO (and actually I’d prefer specific identification but I digress) then the oldest shares often have a different price than my average price per share. So when I sell shares with a higher price than the average price the reallised capital gain is less than if I sold more recent shares. So according to my spreadsheet the remaining shares in my portfolio have a higher unrealised capital gain than what sharesight shows in the “My Portfolio” view. For example, my spreadsheet shows a $44k gain and sharesight shows a $35k gain. So that is a material error.
Obviously the realised capital gains report has to know what shares are sold against which parcels to calculate a correct capital gain for tax purposes however the reporting on the front screen of my Portfolio also needs to remember which actual parcels have been sold to calculate its capital gain accurately as well.