Small depositor Achievement
Research Banking 5 and take a deposit with small interest
When the quest is available, you need to research your Banking up to level 5, if you haven’t already. Once you have this, you can make short and long term loans, with varying degrees of interest (you can at lower bank levels, but the interest is negligible). Take out a short term loan, and wait until the end of the term (as short as 4 hours), and when you collect with your interest, your reward will unlock and pop the achievement.