The market saw a fresh meme stock frenzy this week. While high exuberance can be a contrarian sell signal, sources say the market is still in good shape.

Shares in a donut chain, camera company and meat-substitute maker surged Wednesday in a revival of meme stocks. Krispy Kreme, the North Carolina-based chain with about 350 shops, soared as much as 25% on Wednesday. GoPro, famous for its miniature action cameras, jumped 49% while Beyond Meat rose 11%.