Below is the
exact wordings from the t&cs:
https://av.sc.com/sg/content/docs/sg-esaver-account-tnc.pdf
4. “Customers with wealth holdings” are defined as customers who hold either an Eligible Investment Product or Insurance Product purchased through the bank. An “Eligible Investment Product” refers to (i) Unit Trust(s), (ii) Bonds, (iii) Structured Notes, or (iv) Equities.
5. Your eligible Bonus Interest Rate is assessed based on your wealth holdings at the end of each calendar month during the promotion period.
It is clear that you can buy once & just hold it, OR buy/sell multiple times but always ensure there is something remaining at each month-end.