“ [The meme-stock] surge is powered by advances in trading technology, wider use of leverage, and the rapid expansion of the options market. Confidence among retail traders is notably higher, fueled in part by recent gains in crypto markets,” wrote Mark Hackett, chief market strategist at Nationwide.

Shares in Krispy Kreme donuts, camera maker GoPro, and retailer Kohl's have risen dramatically this week, driven by online hype.