BlackRock Inc. issued and sold more shares than it was authorized to in its iShares Gold Trust, which could lead to penalties by regulators.

The money manager issued and sold 24.9 million shares between Feb. 19 and March 3 that were in excess of the amount it registered with the U.S. Securities and Exchange Commission, according to a regulatory filing on Monday. The failure was “inadvertent,” BlackRock said in the filing.

“In 23 years in the ETF business, I’ve never heard of this,” said Dave Nadig, director of exchange-traded funds at FactSet Research Systems. “Whether it actually is anything more than a hand wave by the SEC to grandfather the new shares, or whether it will actually be an issue, I simply have no idea. This is pretty undiscovered country.”

BlackRock, the world’s biggest money manager, resumed issuing shares in its $7.8 billion gold ETF this week after temporarily suspending them on Friday. The company may be required to repurchase the excess shares at the original price plus interest if investors decide to exercise their rescission rights, according to today’s filing. It also may face penalties by U.S. and state regulators, the firm disclosed.

The gold fund isn’t a typical ETF. It is registered as an exchange-traded commodity, and regulations require that the firm make a filing when it wants to create new shares in excess of those already registered.