Japanese crypto exchange reports bitcoin theft worth $305M

DMM Bitcoin said customer bitcoin deposits “will be fully guaranteed” in the wake of the hack

article-image

Artwork by Crystal Le

share

A Japanese crypto exchange operator said Friday that it suffered an “unauthorized leak” of more than $300 million worth of bitcoin.

The details were shared in a blog post published by DMM Bitcoin. The total amount said to be stolen was 4,502.9 BTC, worth $305.1 million at current market prices.

The exchange said that customer bitcoin deposits “will be fully guaranteed as we will procure the equivalent amount of BTC that was leaked with support from our group companies.” DMM Bitcoin offered no timeline on when these procurements would take place.

DMM Bitcoin said the theft occurred at 1:26 p.m. Tokyo time. That time roughly aligns with the timing of a transaction worth 4,502 BTC flagged by the Whale Alert account on X, formerly Twitter. 

DMM Bitcoin said that it has stopped processing crypto withdrawals and spot market purchase orders, as well as new leveraged trading positions. The exchange is also “screening” new account openings.

Withdrawals denominated in yen, the exchange said, “may take longer than usual,” per the blog post.

The exchange didn’t say when services would resume, but that a separate announcement would be published with more information. 

According to a report from Japanese news service Nikkei, DMM Bitcoin had approximately 370,000 customer accounts at the end of 2023, citing an annual business report. 

If confirmed, the amount stolen represents one of the largest-ever crypto exchange attacks.

In 2018, Coincheck suffered a theft worth 58 billion yen, or about $533 million worth of crypto. The exchange was acquired by online brokerage firm Monax later that year.

Japan was home to arguably the most infamous of bitcoin exchange collapses, Mt Gox, with losses valued at more than $400 million in 2014 prices. The failure of Mt Gox kicked off a decade-long process that appears nearing completion, with preparations underway to finally distribute funds to creditors.


Get the news in your inbox. Explore Blockworks newsletters:

Tags

Upcoming Events

Old Billingsgate

Mon - Wed, October 13 - 15, 2025

Blockworks’ Digital Asset Summit (DAS) will feature conversations between the builders, allocators, and legislators who will shape the trajectory of the digital asset ecosystem in the US and abroad.

Industry City | Brooklyn, NY

TUES - THURS, JUNE 24 - 26, 2025

Permissionless IV serves as the definitive gathering for crypto’s technical founders, developers, and builders to come together and create the future.If you’re ready to shape the future of crypto, Permissionless IV is where it happens.

Brooklyn, NY

SUN - MON, JUN. 22 - 23, 2025

Blockworks and Cracked Labs are teaming up for the third installment of the Permissionless Hackathon, happening June 22–23, 2025 in Brooklyn, NY. This is a 36-hour IRL builder sprint where developers, designers, and creatives ship real projects solving real problems across […]

recent research

Featured.png

Research

Helium stands at a pivotal moment in its evolution as a decentralized wireless network, balancing rapid growth, economic restructuring, and global expansion. With accelerated growth in domestic DAUs and Hotspots supporting its network, Helium is leveraging strategic partnerships and innovative proposals to scale internationally. The recent implementation of HIP 138, “Return to HNT,” has unified its token economy under HNT, simplifying participation and strengthening liquidity, while HIP 139’s phase-out of CBRS refocuses efforts on scalable Wi-Fi offload. Meanwhile, governance shifts under HIP 141 raise questions about centralization as Nova Labs consolidates control over the roadmap.

article-image

P2P Foundation founder Michel Bauwens revealed this week that Satoshi wrote him over email in the early days of Bitcoin

article-image

A Blockworks Research report looked at how Hyperliquid has maintained its hype and how it can build out its businesses

article-image

Dragonfly’s Rob Hadick discussed how the firm is approaching investments in the current market

article-image

The asset surged over the past seven days to reach its highest-ever weekly close on the SOL/ETH pair

article-image

Industry watchers note that SOL ETFs have attracted a fraction of the demand for bitcoin and ether ETFs

article-image

Tariff swings impact stock market and company outlooks, with Apple and NVidia likely to be affected by China tariffs