As investment gurus like Jeremy Grantham warn of a “true, crazy mini-bubble” in the Bitcoin market, the wirehouse firms are telling advisors and investors that products related to this cryptocurrency are not being sold on their platforms.

Merrill Lynch moved to end client purchases of the Grayscale Bitcoin Investment Trust on Dec. 8, for instance. It also does not allow advisors and clients to trade Bitcoin futures, which began trading Dec. 10.

“The decision to close GBTC to new purchases is driven by concerns pertaining to suitability and eligibility standards of this product,” the firm said at the time in a memo. (Clients who invested in the Bitcoin fund before Dec. 8 can, however, keep these assets in brokerage accounts.)

As for Morgan Stanley, “Our financial advisors currently do not offer our Wealth Management clients access to securities or derivatives linked to the price of Bitcoin or other digital currencies,” according to a spokesperson.

While UBS Americas declined to comment on the record, sources familiar with the firm say that it is not facilitating any access to Bitcoin or related products — including futures — as it  does not consider the cryptocurrency an asset class.

“While cryptocurrencies have a number of advantages over mainstream currencies, the chief investment office of [UBS] Americas-Wealth Management is doubtful that they will ever become a mainstream means of exchange, and thinks the sharp rise in cryptocurrency valuations in recent months is a speculative bubble,” according to an October 2017 report.

Wells Fargo Advisors does not allow trading in Bitcoin futures or the Grayscale trust, a spokesperson told ThinkAdvisor.

News of Merrill Lynch’s ban on Bitcoin was first reported by the Wall Street Journal on Wednesday.