Canadian bank Canaccord Genuity is seeking approval from FINRA to act as a custodian for US investors.

If approved, the move could solve one of the biggest pain points preventing institutional investors from pouring billions into the US cannabis industry.

Cannabis remains federally illegal in the US, though that hasn't stopped investors and banks from strategizing around the booming industry.

One of the biggest pain points preventing multibillion-dollar institutions from investing in the US cannabis industry may soon be solved.

Canaccord Genuity, a mid-size Canadian investment bank, is seeking approval from the Financial Industry Regulatory Authority (FINRA) to act as a custodian for US investors, according to a source familiar with the matter.

A custodian bank holds stock and settles trades for funds that invest in publicly traded stocks. Think of them like the plumbing that allows investors to safely buy stock in public companies.

Cannabis industry sources speculate that the bank, which is already very active working with cannabis companies, will use the FINRA approval to act as a middleman between big asset managers like Fidelity, JP Morgan, and BlackRock and Canadian Securities Exchange-listed US marijuana companies like Curaleaf and Green Thumb Industries.

This could potentially pave the way for billions of dollars of investment from US asset managers.

BlackRock president Rob Kapito said at a Toronto conference last year that the firm "will be getting in" to the cannabis industry once custodians are able to clear cannabis stocks.

Representatives for Canaccord and FINRA declined to comment.

Canaccord has built up a lucrative practice advising cannabis companies in recent years. The bank has advised on $5.9 billion worth of cannabis deals since 2017 and has helped bring 64 cannabis companies public in Canada — amounting to $1.86 billion — over the same time period, according to data provider Dealogic.

Read more: 'My lips are wet, my mouth is watering to get a piece of that': A war is brewing between US and Canadian marijuana companies to claim a $75 billion market

While Canaccord is one of the most active Canadian investment banks, it has doesn't yet have a large US presence.

Because cannabis is federally illegal in the US, the government could, in theory, prosecute banks that work with US cannabis companies under federal money laundering laws. That situation poses a big problem for investors who want exposure to publicly traded marijuana companies that operate in the US: most banks won't touch the industry.

That's severely limited the amount of capital US cannabis companies, known as multi-state operators, can raise, according to many senior cannabis executives Business Insider has spoken with. It also means raising money is more expensive — and in an industry in a rapid phase of growth and consolidation, that can make or break a company.

But investors and banks are strategizing around how to get into cannabis. Business Insider previously reported that senior executives at Citigroup have held talks about how closely it should work with cannabis companies or clients in other industries who want a loan to invest in the marijuana market.

The potential upside for investors is huge: According to some Wall Street analysts, the US cannabis market could skyrocket to $75 billion by 2030. For comparison, the cigarette industry in the US is worth roughly $80 billion, according to the investment bank Cowen.