Something hip and fun, but not aggressive. Sophisticated yet enticing.
The t-shirt is for a startup that helps people with the stock market.
One example of something I like (because of all the lines and colors) is this: https://blog.arduino.cc/wp-content/…atured.png
However, that example is just one example and I'm not saying it needs to look like that. I just like how the lines are all different colors and it's complex, interesting, and creative.
One specific idea I have in mind is a large version of the circular logo, but instead of each part being a solid color, the three parts are filled with stock ticker symbols (AAPL, NVDA, AMZN, etc.) and/or lines similar to a line graph going up and down. When viewed from afar, it mostly just looks like the logo, but taking a closer look reveals the stock-market themed items inside the logo.