European and Canadian regulators have started to crack down on the problem, too.

Canadian regulators began their review of the project this week.

United States and Canadian regulators still need to approve the deal, as do shareholders.

The Canadian regulators said the company had not provided enough information about its problems for investors to make informed decisions.

Even if Canadian regulators lift the trading ban, she said, it will be "virtually impossible" for large investors to sell shares outside the exchanges.

Under antitrust laws, the transaction must be approved by American and Canadian regulators.

In January, Canadian regulators asked manufacturers to recall products containing high doses of the supplement.

And the message from Canadian regulators today was that nothing should be taken for granted.

The merger must be approved by Canadian regulators.

For Canadian regulators, this led to some concerns.