If I had to guess, the Fidelity Active Trader Pro app. It's a pretty handy app, that seems to be constantly up to date, but it's garbage on Mac, so I setup a P

If I had to guess, the Fidelity Active Trader Pro app. It's a pretty handy app, that seems to be constantly up to date, but it's garbage on Mac, so I setup a PC laptop next to my main setup so I can have it running. Still a bit finicky on PC, but way better.