The brokerage arms of Bank of America Corp.'s Merrill Lynch and Wells Fargo & Co. have begun offering ETFs that invest directly in Bitcoin, underscoring the acceptance of such products by mainstream investment banks. Higher and higher.

According to people familiar with the matter, these banks are offering approved ETF products to some financial customers with brokerage accounts.

In January, more than 10 Bitcoin ETFs received approval from U.S. regulators, a landmark decision that triggered a surge in demand for Bitcoin ETFs. But even with regulatory approval, whether to offer trading in Bitcoin-related products is still up to the companies themselves, and some may be reluctant to get involved in this volatile asset class.