Each Stak has an index value, that shows how the Investak is performing. Set to 1000 at inception, the current value shows how much the Stak has moved since it was created. Assuming a hypothetical investment of Rs.1000 in the Stak on the inception date, the index value is set to 1000. If the index value of the Stak is 1100 after 30 days, it means that the hypothetical investment of Rs. 1000 has grown up to Rs. 1100 now (your Cluster is up by 10%).