Investing.com - Cryptocurrencies were tumbling across the board on Friday as concerns over the future of the industry escalated, leading some analysts to suggest that the bubble was finally bursting.

Wave after wave of negative news has hit the digital currency market this week, driving its leader by market cap, Bitcoin to its worst weekly performance since 2013.

Amid increasing regulatory scrutiny on the global level, Japanese tax authorities reportedly raided Coincheck’s offices Friday morning, hauling out documents and computers as evidence. The move came after the crypto exchange was hit by hackers that heisted more than $500 million worth of the virtual currency .

This week South Korean authorities began to prohibit the opening of anonymous digital currency accounts, as well as implanting a minimum age for trading.

India’s finance minister pledged to eliminate the use of cryptocurrencies in criminal activities, implying that stricter regulation is around the corner.

In the U.S., Bloomberg reported this week that the Commodity Futures and Trading Commission (CFTC) had subpoenaed crypto exchange Bitifinex and the cryptocurrency firm Tether, which runs its own that it claims is pegged to the dollar, amid accusations of price manipulation.

While Tether has said all of its coins are backed by U.S. dollars held in reserve, the company has yet to provide conclusive evidence of its holdings to the public or have its accounts audited.

Some accusations suggest that Tether is creating coins out of thin air and using those to purchase digital currencies via Bitifinex, thus artificially inflating prices.

Bitcoin briefly dropped below $8,000 on Friday as the wide-spread selloff continued to hammer cryptocurrencies. The largest digital coin by market cap has tumbled nearly 40% so far this year and has crashed approximately 58% since its all-time high near $20,000 reached last year.

The market cap of global cryptocurrencies was situated Friday at just under $394 billion, compared to $800 billion at the beginning of 2018.

At 8:00 AM ET (13:00GMT), actually performed “better” than other rivals that were also tanking on Friday. It was last off around 11%, or $1,065, at $8,350.

By descending market cap, sank 22% to $885, tumbled 23% to $0.7900, while Bitcoin offshoot slumped 18% to $1,105.50.