Shares of the still-fledgling cannabis industry mainstays like Canada’s Aphria, Aurora, and others rose anywhere from 1% to more than 4% after Boehner’s surprise announcement, outpacing broader markets. Aurora Cannabis was up 2.5% in early Wednesday trading; the U.K.’s GW Pharmaceuticals, which is vying for the first Food and Drug Administration (FDA) approved cannabis-based medicine in the U.S., rose more than 2%; Canada’s MedReleaf spiked 4% while Aprhia had a more modest 1% rise.

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Boehner, a Republican ex-Congressman from Ohio, opposed marijuana legalization while he served in the House of Representatives before stepping down towards the end of 2015. But he cited an evolution in his thinking on Wednesday, reflecting a broader shift in how the public (and politicians) view marijuana decriminalization, legalization, and research. Boehner specifically cited the potential of medical marijuana to help stave off the opioid epidemic as a rationale for his changed thinking.

I’m joining the board of #AcreageHoldings because my thinking on cannabis has evolved. I’m convinced de-scheduling the drug is needed so we can do research, help our veterans, and reverse the opioid epidemic ravaging our communities. @AcreageCannabis https://t.co/f5i9KcQD0W

— John Boehner (@SpeakerBoehner) April 11, 2018

“We need to look no further than our nation’s 20 million veterans, 20% of whom, according to a 2017 American Legion survey, reportedly use cannabis to self-treat PTSD, chronic pain, and other ailments,” said Boehner and former Massachusetts Governor Bill Weld, a libertarian who is also joining Acreage’s board of advisors. “Yet the [Department of Veterans Affairs] does not allow its doctors to recommend its usage. There are numerous other patient groups in America whose quality of life has been dramatically improved by the state-sanctioned use of medical cannabis.”

Acreage Holdings is an all-purpose marijuana company that handles operations such as cannabis cultivation, processing, and managing dispensaries. It’s a growth industry given that 30 states and the District of Columbia have broadly legalized the use of cannabis in some shape or form, and eight states, plus DC, have legalized recreational marijuana use outright.

This is Boehner’s second major foray into a “vice” industry—in the fall of 2016, Boehner (a notorious cigarette smoker) joined the board of tobacco giant Reynolds American, which makes popular cigarette brands like Camel, Newport, and Pall Mall.