Stock Points track the value of the associated real company share. This means that the value of your Stock Points will fluctuate with the real stock market.
While the value of your Stock Points will change, the amount of Stock points you've earned will not change. 100 Stock points is always equal to 1 share, but the value of the points will differ according to the share price.
For example, if company A has a share price of €100, each Stock point is worth €1. If you have 20 Stock points from this company, they will be worth €20.
If company B has a share price of €10, each Stock point is worth €0.10. This means that 20 Stock points from company B are worth €2.