When a Canadian marijuana company listed on the Nasdaq last week, most in the cannabis industry said it was an important milestone in the fight toward legitimization.

"Every success means future success for the industry. Every successful investment, every successful individual and every successful company brings us closer to legalization," said Patrick Rea, the co-founder of CanopyBoulder, a firm that gives financial backing and advice to startups in the industry.

It is a sign of change even though U.S. cannabis companies remain relegated to alternative exchanges. In the U.S. marijuana is prohibited under federal law, despite being legalized in several states.

Toronto-based Cronos Group owns medical marijuana growing and distribution operations in Australia, Canada, Germany and Israel — all countries where medical marijuana is legal. The company made history last Tuesday by becoming the first "plant-touching" cannabis company, or company that deals directly with the cannabis plant, to list on a major U.S. exchange.

It is also listed to trade in Canada and Germany.

"It is a significant signal that a major U.S. exchange does not have an issue with cannabis, but rather the U.S. federal status," wrote Hadley Ford, CEO of iAnthus Capital, a U.S. cannabis company listed on the Canadian Securities Exchange.

Cronos Group stock isn't the first marijuana-related asset to make it to a major U.S. exchange.

In December, Alternative Harvest ETF, a fund that trades on the NYSE Arca, started investing in marijuana companies — Cronos Group, included. By March, it had increased its assets under management to more than $400 million and given investors access to a basket of marijuana stocks.

But Cronos Group's listing on the Nasdaq represents the first time investors can get behind a specific cannabis stock.