Not for the first time, Andreas Utermann, the CEO of investment management firm Allianz Global Investors, has taken a swipe at digital currencies.

In a Jan. 30 column headlined “Unencryptoed: Why investors should steer clear of cryptocurrencies,” Utermann said the distributed ledger technology lacks key features that make fiat money sustainable, including tax-raising powers, productivity in terms of trade and the ability to pay interest.

“As an asset, a cryptocurrency is a claim on nobody — in contrast to sovereign bonds, equities or paper money — and it does not generate an income stream,” he wrote. “As a currency, it is only a medium of exchange for larger-ticket items, and is simply too volatile to be considered as a numeraire or a store of value,” concluding it makes cryptocurrencies “unsuitable for investing in”:

‘This makes cryptocurrencies entirely unsuitable for investing in. As such, I would expect policy makers to take a close interest in the emergence of initial coin offerings (ICOs) that are being marketed as investments and a home for individuals’ savings.’

Andreas Utermann, Allianz Global Investors

Read: Bitcoin is about to do something it has never done before — hint: it’s not good

This is not the first time the former Merrill Lynch

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banker has poured cold water on the viability of crypto assets. In December 2017, when the price of bitcoin

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was flying high, he told Bloomberg Television the cryptocurrency was “pretty valueless,” saying he would rather have something you can hold or see like the Mona Lisa painting:

Then a year later, at a panel discussion in London, Utermann said cryptocurrencies should be outlawed, adding, “I am personally surprised that regulators haven’t stepped in harder.”

Rounding out Wednesday’s post, Utermann said bitcoin mining — the process by which bitcoins are created — is a drain on the environment, so much so that society can’t afford an increase in popularity. “[I]f we consider the environmental costs of mining cryptocurrencies — where the energy consumption related to a single year’s production of bitcoin was equivalent to the annual energy consumption of Ireland — we cannot afford for them to increase in popularity.”

Read: Here’s how much it costs to mine a single bitcoin in your country

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