Thodex, one of Turkey’s largest cryptocurrency exchanges, collapsed on April 20, 2021, when founder and CEO Faruk Fatih Özer froze all withdrawals, suspended the platform, and boarded a flight to Albania — leaving approximately 391,000 registered users locked out of accounts holding funds estimated at roughly $2 billion. The exchange had operated since 2017 under the name Koineks before rebranding as Thodex in March 2020. Özer was 27 years old at the time of the exit.
Turkish prosecutors launched an immediate investigation. Özer was arrested in Vlora province, Albania in August 2022 after more than 16 months as a fugitive. He was extradited to Turkey in April 2023. On September 7, 2023, an Istanbul court convicted Özer and several of his siblings of aggravated fraud, money laundering, and criminal organisation charges, and sentenced him to 11,196 years in prison — one of the longest sentences ever imposed in Turkey. On appeal, the Istanbul Regional Court of Justice upheld the fraud and money laundering convictions in early 2025 but dismissed the organised-crime charge and ordered a limited retrial on that element. Özer remained incarcerated pending the retrial. On November 1, 2025, he was found dead in Tekirdağ F-Type High Security Closed Penitentiary. Authorities reported he was discovered hanged in the bathroom; the Istanbul prosecutor’s office opened an investigation and the body was transferred to the Institute of Forensic Medicine. The cause of death remained under formal inquiry at the time of this report.
The estimated loss figure of $2 billion, widely cited by Turkish prosecutors and international media, reflects the claimed value of cryptocurrency held in Thodex accounts at the time of the freeze. Because Thodex operated as a closed order-matching system without publishing audited proof-of-reserves, the true value of cryptocurrency under management has never been independently verified from blockchain records. The figure should be treated as the prosecutors’ working estimate rather than a fully audited loss amount.
Africrypt, a South African cryptocurrency investment platform founded in 2019 by brothers Raees Cajee and Ameer Cajee, collapsed in April 2021 after the founders claimed a hack had drained investor wallets and then instructed clients not to report the incident to authorities — a step they framed as protecting an ongoing recovery effort. Within days of that announcement, both brothers were unreachable. Client funds were gone.
The collapse attracted global attention primarily because of a headline figure: early reports, including a widely cited Bloomberg article from June 2021, placed losses at $3.6 billion, a figure derived from the claimed Bitcoin holdings at peak valuations. That number has not been verified by any regulatory body or court-appointed investigator. The Financial Sector Conduct Authority (FSCA), South Africa’s markets regulator, estimated investor losses at approximately R200 million (around $12–15 million at 2021 exchange rates) based on formal complaints received. Court-appointed liquidators working from documented fund flows put the credible upper bound at roughly $223 million. Independent analysts have cited a $40–50 million range as the most supportable estimate given available records. The gap between $3.6 billion and verified figures is substantial; this entry uses the FSCA and liquidator ranges and notes the discrepancy.
As of early 2026, Raees and Ameer Cajee had returned to South Africa from their years abroad and were reported to be residing inside a gated estate in KwaZulu-Natal. No formal criminal charges had been filed in South Africa. One brother was arrested in Zurich, Switzerland in November 2021 and later released on bail to supervised residence. South African authorities have not effected a domestic arrest, and lawyers for investors reported difficulty serving legal papers as of early 2026.
FCoin, a Chinese cryptocurrency exchange founded in May 2018 by Zhang Jian, a former chief technology officer of Huobi, permanently closed on February 17, 2020, after Zhang publicly announced that the exchange had accumulated a deficit of between 7,000 and 13,000 Bitcoin — worth up to $130 million at prevailing prices — which it was unable to cover. Zhang attributed the deficit to compounding errors in FCoin’s signature innovation, a “transaction-fee mining” reward model, combined with treasury management failures and an undisclosed buyback programme for the exchange’s native token. The platform did not suffer a hack, and Zhang did not immediately flee in the manner of a conventional exit-scam operator; he published an extended written explanation and stated his intention to use proceeds from future ventures to repay users. He then became effectively unreachable.
Users were paid nothing. Blockchain researchers at AnChain.AI reported in February 2020 that funds had been moved from FCoin’s cold wallets to unknown accounts in the days before the closure announcement, raising the question of whether the deficit narrative was genuine insolvency or a cover for a planned exit. Chinese authorities investigated but no formal criminal charges against Zhang have been publicly confirmed in Chinese or international legal records as of this writing. Zhang’s whereabouts and legal status remain undisclosed.
FCoin occupies an unusual position in the taxonomy of crypto custody failures: it sits in the contested territory between catastrophic negligence and deliberate fraud. The factual record supports both readings. This entry presents the documented facts and notes where the record is genuinely ambiguous.
ACX Exchange, the cryptocurrency trading platform operated by Melbourne-based Blockchain Global Limited under the domain ACX.io (associated with Bitcoin.com.au), collapsed in late 2019 when customers found themselves unable to withdraw funds or cryptocurrency assets. Total unsecured creditor claims lodged with liquidators reached A$58,648,886 as of October 2023, of which A$22,753,442 represented claims from former ACX Exchange customers — a figure regulators describe as likely understating actual user losses given that many affected account holders did not file formal claims. Blockchain Global entered voluntary administration in October 2021 and liquidators were formally appointed on February 11, 2022.
The platform was operated under the direction of co-founders and directors Sam Lee and Liang “Allan” Guo, alongside co-founder Vincent Vu. Liquidator reports filed with ASIC in November 2023 identified potential breaches of the Corporations Act by current and former officeholders. ASIC commenced a formal investigation in January 2024 and filed civil penalty proceedings against Allan Guo in the Federal Court. A further development came on June 3, 2026, when the Federal Court stayed those civil proceedings pending a decision by the Commonwealth Director of Public Prosecutions on whether to lay criminal charges — an indication that the evidentiary threshold for criminal prosecution was under active assessment. As of that date, Guo had departed Australia on September 23, 2024, following the expiry of travel restraint orders, and had not returned.
The roughly 22,000 individuals who filed creditor claims were ordinary Australian retail investors who had deposited cryptocurrency and fiat currency into what presented as a professionally managed exchange. Active since approximately mid-2016 under the Bitcoin.com.au brand, it positioned itself as part of Australia’s legitimate crypto infrastructure. Users who lost funds have received no distribution from the liquidation estate to date.