Toronto-based TMX Group Ltd. is “engaged” with the Canadian Securities Administrators regarding the clearing of securities of issuers with marijuana-related activities in the United States, the stock exchange operator said Thursday.

“This is a complex matter which touches multiple aspects across our capital market system, and as such requires close examination and careful consideration,” TMX says in a statement.

The company is the owner and operator of The Canadian Depository for Securities (CDS), Canada’s equities and fixed income clearing house. Other TMX subsidiaries include the Toronto Stock Exchange (TSX), TSX Venture Exchange, TSX Alpha Exchange and the Montreal Exchange.

The announcement is intended “to clarify to the marketplace that there is no CDS ban on the clearing of securities of issuers with marijuana-related activities in the U.S., despite media reports,” TMX says.

“We are working with regulators to arrive at a solution that will clarify this matter for issuers, investors, participants and the public,” the company adds.

The Globe and Mail reported last week that CDS was considering a prohibition on clearing trades in such issuers.

Investors have expressed frustration over what they say is TMX’s murky position on allowing cannabis firms with U.S. operations to list on its exchanges. The drug has been legalized in some form in many states but remains illegal under U.S. federal law.

Canadian marijuana companies have so far dealt with the uncertainty by sticking to the U.S. medical cannabis market or ancillary businesses and listing their U.S. investments on the smaller and less risk-averse Canadian Securities Exchange.

With files from The Canadian Press