for the tax implications bottom line is whether you carry out trading as a business or as an investor. That is whether you are conducing yourself in a business like manner.
On top of that you have capital gains considerations and these you can mix and match for yourself.
You can make the decision yourself whether you account for the value of a share at sale price or at and end of financial year valuation. And you can account for some of your portfolio one way and some another.
If you hold a share for years you can either keep track of it year to year - or on a buy once sell once - or even a mix. That is write it down this year if its a loss - but account for its final selling value as profit from this accounting point when you finally sell at some point in the future (if it comes up)
In the end of the day treat it as a business buying and selling things.
Somethings you would do a stock take on from financial year to financial year, some you may hold for a longer period - perhaps years which you will account for only when sold. Some things you may sell on a day to day basis - all of which need to be accounted for. Some things may have depreciated and you want to offset that loss against appreciation elsewhere.
Long as it all adds up.
Imagine you are running an antique store where you are buying stuff in the hope it appreciates over time but some - perhaps a lot depreciates. Somethings move quickly some slowly. Some you will have a capital gain over years etc etc.
