U.S. spot bitcoin exchange-traded funds (ETFs) appear to be on the verge of launching after the exchanges that will list them filed amended documents, suggesting they expect U.S. Securities and Exchange Commission approval in the coming days.

The amended 19b-4 filings, filed on behalf of BlackRock, Grayscale, Fidelity and other issuers, join last month's amended S-1 filings, addressing feedback from the U.S. Securities and Exchange Commission (SEC). More than a dozen applicants hope to launch the first spot bitcoin ETFs in the U.S.; it's likely multiple issuers will be approved simultaneously.

Individuals at two different issuers told CoinDesk on Thursday that their companies anticipate approvals sometime next week.

One of the individuals told CoinDesk that filing the amendments did not mean approvals were guaranteed but said they were optimistic.

A final deadline for SEC action for at least one application, by Ark 21 Shares, is Jan. 10, suggesting the regulator may approve all of the final applications it is comfortable with by that date.

This filing "is another important step towards uplisting GBTC as a spot bitcoin ETF," Grayscale spokeswoman Jenn Rosenthal said in a statement, referring to the company's bitcoin trust that it wants to turn into an ETF. "At Grayscale, we continue to work collaboratively with the SEC, and we remain ready to operate GBTC as an ETF upon receipt of regulatory approvals."

Earlier Friday, Bloomberg reported that the SEC's commissioners were "expected to vote on the exchange-rule filings next week."

The regulatory agency needs to approve both the 19b-4 filings and the S-1 filings before the ETFs can launch.