What happened

Talk about a buzzkill: The latest news on marijuana reform didn't go over well with cannabis stock investors. On Tuesday, they sold off many sector favorites, including Aprhria (APHA), Aurora Cannabis (ACB -2.96%), OrganiGram Holdings (OGI -1.03%), HEXO (HEXO), and Curaleaf Holdings (CURLF 2.02%). All fell at rates ranging from 3.4% to 4.5%. Meanwhile, multistate operator Green Thumb Industries (GTBIF 2.46%) really took it on the chin, declining 8.4%.

So what

There was little news of any consequence from those companies. Rather, it seems that investors are reacting to one development in Washington that's encouraging on its surface. Following a similar move in the House of Representatives last week, Sen. Jeff Merkley, an Oregon Democrat, and his Republican counterpart Steve Daines of Montana have reintroduced the SAFE Banking Act in the Senate.

Marijuana leaf atop a $1 bill.

Image source: Getty Images.

But Democrats, who tend to support marijuana reform measures, only control the Senate these days because of the potential tie-breaking vote of Vice President Kamala Harris, and the Senate filibuster is still available to Republicans (who clearly intend to do their best to scotch Democrat initiatives). That means the SAFE Banking Act -- which would protect financial institutions in legalized states that want to offer basic banking services to marijuana businesses -- currently looks like a nonstarter there.

Now what

So the one-step-forward-and-two-steps-back lurch of U.S. marijuana reform continues. But shareholders of Aprhia, Aurora, and their fellow cannabis stocks shouldn't be discouraged. Momentum still favors progress, as witnessed by the recent recreational-legalization switch thrown by Virginia. Believers in the future of corporate weed should stay the course.