Why do I have a negative time-weighted return, but positive dollar return?

The logic is entirely the same as the inverse situation mentioned above. Your TWR is negative because your portfolio’s return has decreased in value since the first deposit you made with us.

Here’s an example of when this might be the case:

Let’s say you deposited RM 100 to start your StashAway account in January and the market goes down 10% by September. You’ve lost RM 10 (out of RM 100 invested) in your portfolio and you’re down to RM 90. You then again have an unexpected windfall (lucky you!) and decide to make a RM1,000 deposit in September. By December, the market goes up 5% after the second tranche of investment. 

What are my returns like now? Well, you would have positive dollar gains because you just gained about RM 44.50 on a total of RM1,100 invested.

But this was not because the portfolio has performed exceptionally thus far: it went down 10% then up just 5%. However, most of your money was invested right before markets went up.

The time-weighted return is negative because the first deposit of the investment performed poorly between January and December, but your simple dollar return is still positive because of when you decided to make your deposits.