"strong on charts"
Mark is a guy who trades. You know, the guy who sits there, looks at charts, can guess where the price of a stock or cryptocurrency or whatever is going to go. He's all on the screen, cofee in hand, eyes red because he spent half the night analyzing the market. He's got a bunch of tabs open: TradingVie, news, some forum where everyone is saying Bitcoin is either going to skyrocket to millions or crash to something.