What happened

Shares of AMC Entertainment Holdings (NYSE:AMC), GameStop (NYSE:GME), and Sundial Growers (NASDAQ:SNDL) were all down in midday trading Friday despite the market indexes continuing their bullish run higher.

The movie theater operator was down 3.5% heading toward noon, while the video game retailer was almost at breakeven, and the marijuana producer was off 2.1%. The Dow Jones Industrial Average was advancing 225 points for a 0.6% gain.

Arrow over $100 bills pointing down

Image source: Getty Images.

So what

There wasn't any news directly related to any of these stocks, but that hasn't been necessary to drive them higher or lower, as chatter in internet chat rooms has more often than not been the deciding factor.

Too often traders discuss hedge funds, dark pools, and short-sellers that need to be defended against rather than the merits of the companies' specific business model. Too often the stocks are the ones holding the weak hands, regardless of who is backing them.

Now what

None of these companies are going out of business, at least not anytime soon, and each feasibly has a plan of attack to recover its foundational footing and grow again. 

Because AMC, GameStop, and Sundial all still trade at inflated valuations in relation to where they were prior to the trading frenzy at the start of the year, it means there's probably more downside risk to the stocks than further upside potential. 

Investors would be wise to block out the noise and once again return to the fundamentals of a company to determine its worth as an investment. 

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.