Stock Traders Reap Billions With Stampede Into Online Learning

Many families have found they hate remote learning for their grade-school kids. But a whole other group just loves it: investors in online-education companies.

Shares of Chegg Inc., a Silicon Valley company specializing in homework help, have soared more than 120% this year. K12 Inc., which operates online public schools, has doubled. Boxlight Corp., a Georgia company that sells classroom and teacher-training software to schools, is up 203% since April.

But some skeptics worry the enthusiasm may be getting out of hand. They say the shares of some of the publicly traded companies have become darlings of ...