Sales of so-called marijuana stocks have soared after California legalised marijuana at the end of last year. There is now talk of a "grass rush".
"It feels like a new Klondike or something," said Joakim Bornold, an economist at Nordnet. "A lot of people are seeing an opportunity here to make money."
Tens of thousands of Swedes have also bought marijuana stocks, even though cannabis use, whether for recreational or medical purposes, is illegal in Sweden.
Bornold said he believes it is up to individuals to decide whether investing in a marijuana manufacturer is ethical or not, and he warned that this booming market is also a high-risk one.