The current value of your investment is the amount that you initially invested, with the impact of the Multiplier (see: what does the Multiplier option do?), and the change in value of your products, taken into account.
You bought £100 in Stocks, without a Multiplier, and you stated that you thought the value would increase. Subsequently, the value of these Stocks increased by 5%. This means the current value of your investment is £105.
However, if you would've bought these Stocks with a Multiplier of 3, the current value of your investments would have been £115.
The current value of your investments is part of the real-time value of your account (see: what's the real-time value of my account?)
If you have any further questions in regards to this, please feel free to contact us via email at BUX Support.