A man walks past a Bitcoin symbol on a window of the offices of the bank 'La Maison du Bitcoin' in Paris.

"The decision to close GBTC to new purchases is driven by concerns pertaining to suitability and eligibility standards of this product," according to an internal memo the newspaper reviewed.

The ban prevents the financial giant's roughly 17,000 advisors from pitching investments related to bitcoin and executing client requests to trade Grayscale's bitcoin investment trust (GBTC) , the newspaper said, citing a person familiar with the matter.

Merrill Lynch financial advisors cannot buy bitcoin -related investments for their clients, The Wall Street Journal reported Wednesday.

A Merrill Lynch spokesperson confirmed the report to CNBC.

Michael Sonnenshein, director of sales and business development at Grayscale, said in a statement to CNBC that, " We look forward to speaking with Merrill Lynch and addressing any questions or concerns they have about the Bitcoin Investment Trust. We are unaware of any similar policies at other brokerage firms."

GBTC is traded over the counter, rather than through a formal venue like the New York Stock Exchange. The bitcoin trust is the top holding of two of Ark Invest's exchange-traded funds, which unsurprisingly were among the top performing ETFs last year, according to ETF.com.

Merrill Lynch previously banned access to the bitcoin futures that CME, the world's largest futures exchange, and its competitor Cboe launched in mid-December.

Bitcoin has soared more than 1,300 percent over the last 12 months and has drawn strong criticism that the digital currency is in a highly speculative bubble.

Read the full Journal report here.