Financial markets once again have been seized by meme-stock mania. In mid-July, a frenzied rally erupted around a cohort of beaten-down companies, including Opendoor Technologies Inc., Kohl’s Corp.

By now most people, even those vaguely tuned into finances, have heard the phrase "meme stock." But if you're just catching up, here are some basics.

Meme-stock mania might be back, but old heads may have noticed that the moves this time around are lacking a certain ...

Shares of doughnut maker Krispy Kreme were up as much as 70% on Tuesday with no clear catalyst, before pulling back the next ...