As investments drift off their targets, the balance in the pie shifts. To fix this, you can rebalance the pie at any time, by tapping the "Rebalance" option at the bottom of the 'Holdings' section.
The rebalancing algorithm will make the necessary adjustments in order to equalize the actual value and the target value of each investment. It will sell some shares of overweight investments and buy more underweight investments. You will get a preview before you execute the rebalancing:
Note: Rebalancing may take time if markets are currently closed, or if you have investments in multiple markets and only some of those markets are currently open. You will get notified immediately after rebalancing has concluded.