Morgan Stanley
Bad news for tobacco companies: America's teens prefer marijuana.

The latest research from Morgan Stanley's tobacco analysts reveals two major trends in teen smoking habits.

First, high-schoolers are smoking fewer and fewer cigarettes. Only 10.3% have reportedly smoked a cigarette in the past 30 days, down from 27.4% in 2000.

And second, the gap between marijuana and cigarette use is widening. Until 2008, cigarettes were the preferred option, but now weed is clearly the go-to for those in high school.

So what does this mean for big tobacco?

"In our view, any industry participation in the legalized marijuana industry is highly unlikely barring the passage of federal legislation legalizing its sale and usage, although we would expect the industry to closely monitor the market's development at the state level," Morgan Stanley's Matthew Grainger writes.

But these companies may soon be asked to do more than just monitor the situation. Other analysts argue that big tobacco companies will have to start addressing questions about marijuana sooner than they think.

"With this quickly changing view of marijuana across the US," RBC Capital Markets' Nik Modi wrote earlier in December, "we believe it is only a matter of time until investors start asking questions about how it will fit into the bigger picture."

"And while every tobacco company management we have spoken to on this topic has been unwilling to discuss it, we believe full federal legalization of marijuana in the US would likely lead tobacco companies to reconsider this space," Modi added.

So as Americans (especially young high-schoolers) increasingly turn toward marijuana, big tobacco companies are really going to have to start thinking about the numbers soon.