What happened

Shares of Zillow (Z -1.86%) (ZG -1.58%) were down 8.9% on Monday, Planet Fitness (PLNT -2.09%) fell 12%, and Camping World Holdings (CWH -1.31%) was off 16.6%.

These three stocks don't have much in common, other than the obvious: They all had the misfortune to be trading publicly on a day when COVID-19 coronavirus cases topped 110,000 worldwide, expanding to infect 105 countries, where the disease has killed more than 3,800 people.

Coronavirus caution printed on a road sign

Image source: Getty Images.

So what

Zillow operates a website that lets you estimate the current value of your home (and can help you sell it). Planet Fitness (surprise!) operates fitness centers, and Camping World Holdings sells campers and other kinds of RVs, as well as providing services to their owners, and selling assorted outdoor equipment. None of these stocks had any news to report Monday. 

But there may be one other thing they have in common: They're all somewhat discretionary, and tend to market to consumers' distractions. Bored homeowners go to Zillow to check in on their home's value, and to see if the neighbors' house that just went on the market is really worth that much. Planet Fitness members spend their time exercising, while Camping World patrons plan their next vacation.

None of these are immediately essential activities -- or at least, they may not feel very essential on a day like today, when the world appears to be falling apart. It's entirely possible that, in the current environment, all three stocks will suffer as consumers are pressured by more immediate health concerns.

Now what

Once the world gets back to normal (and it will, because we have seen even scarier sell-offs than this one before), people's minds may once again return to normal activities such as buying and selling homes, exercising in communal gyms, and taking vacations without fear of running afoul of infections. In the meantime, it's understandable that investors might be a bit leery of the risk of owning shares in unprofitable Zillow or Camping World -- or even in Planet Fitness, at a P/E of 42.

The world may simply not feel safe enough for that anymore.