The interviewer started by explaining the company and how the teams are structured. He then asked me to describe one of my projects and went into depth with follow-up questions. After that, he asked a system design question about building a feature to display a stock price graph. The requirement was to allow users to select a date range (for example, for Apple stock) and define an interval, and then return aggregated data based on that interval. For instance, for the last three months, the data could be grouped by day and the average price calculated for each day.