Bitcoin fell to a 3-1/2-month low on Friday, dragged by uncertainty about U.S. President Donald Trump's tariff plans and crypto policy and flagging investor confidence after a $1.5 billion hack in rival coin ether.

Bitcoin, the world's largest cryptocurrency by market value, was last down more than 5% on the day at $79,666, trading below $80,000 for the first time since November 11.

"Bitcoin's fall below $80k shows that positive sentiments from a crypto-friendly administration and high-profile endorsements have run their course," said Joshua Chu, Co-Chair of the Hong Kong Web3 Association.

The world's largest cryptocurrency has shed a quarter of its market value since mid-December, when it topped $105,000 on optimism that the Trump administration would champion a strategic bitcoin fund and loosen regulation.

Beyond a flurry of appointments of crypto-friendly officials when he took office, there has been little concrete news around that policy for investors.

"Momentum ran out when there was no fresh news to keep driving the bullish narrative," said Kyle Rodda, senior financial market analyst at Capital.com.

"On top of that, given the move in Mag 7 stocks we've seen, which is also a story of momentum slowing and valuations deflating, bitcoin, which still trades as a 'higher beta tech' play, is being dragged down by sell-off in Wall Street tech stocks."

Ether , the second-largest cryptocurrency by market value, was down nearly 6% at $2,149.38, around its lowest since January 2024.

In addition, investors have been pulling money out of bitcoin-backed exchange-traded funds.

Global investors have been jittery on signs the so-called exceptionalism of the U.S. economy might be fading, while Trump prepares to impose tariffs that have stoked fears of higher global inflation and slower growth.

Trump has indicated he plans to slap a 25% levy on imports from Canada and Mexico from early March, and more tariffs on China. In a sign of unease, safe-haven U.S. Treasury prices have rallied sharply, sending yields to three-month lows.

The crypto world has also been nervous after Dubai-headquartered Bybit, the world's second-largest exchange after Binance, said on February 21 that hackers had stolen ether worth around $1.5 billion.

Bybit caters to more than 60 million users worldwide and offers access to various cryptocurrencies, including bitcoin and ether.

Blockchain research firm Elliptic said the hack was probably the single largest known theft of any kind.

"It's a combination of macro forces. The Fed only planning one rate cut, more tariffs, uncertainties around geopolitics and war, and the ByBit hack didn't help confidence either," said Reuben Conceicao, chief strategy officer at digital wallet firm Metasig. "It is hard for people to be excited and pump BTC when there are bigger issues at play."