Court filings that became public on July 14 and 15, 2026, after Circle moved to confirm an arbitration award in Boston federal court, reveal that the USDC issuer banned Heka Funds in December 2023. Circle alleged that Heka's stablecoin arbitrage operation was not independent market activity but a coordinated effort, backed by roughly $800 million in Tether capital, to siphon liquidity from Circle and funnel it to its biggest competitor by market capitalisation. Retired judge Robert Dondero, serving as arbitrator, dismissed Heka's subsequent $49 million damages claim and awarded Circle approximately $166,000 in legal costs.

What Heka Funds Actually Did

Heka Funds is a Malta-registered investment vehicle (a SICAV plc, authorised by the Malta Financial Services Authority) managed by London- and Monaco-based Abraxas Capital Management (regulated by the UK Financial Conduct Authority and Monaco's CCAF). Since late 2018, Heka ran a straightforward stablecoin arbitrage strategy: buy USDC on secondary markets when it trades below one dollar, then redeem it directly with Circle at face value and pocket the difference. This is a standard mechanism that normally helps stablecoins recover their peg after periods of market stress. At its peak, Heka held roughly 540 million euros in stablecoins and carried approximately 193 million euros (around $204 million) in borrowings against those holdings, a leveraged structure that amplified both its returns and its operational scale. The fund delivered cumulative returns exceeding 100 percent since inception and generated 49 million euros in operational profit in 2021 alone. Its on-chain activity is traceable through the Ethereum address 0xb99a2c4C1C4F1fc27150681B740396F6CE1cBcF5.

The problem, according to Circle, was that Heka was doing this at a scale far beyond any comparable market participant, and that the cash it collected from redemptions was flowing back into Tether's ecosystem rather than staying in conventional portfolios.

The Undisclosed Tether Stake

Circle's suspicions hardened when it learned that Tether held a roughly $800 million stake in Heka, representing about 75 percent of the fund's total assets, through a linked vehicle. Heka had not disclosed this relationship. Arbitrator Dondero found that this concealment constituted bad faith. He stopped short of formally ruling that market manipulation had occurred, a distinction Heka's representatives have emphasised publicly. Tether also waived minting fees for Heka, a benefit not offered to ordinary clients.

Dondero described Circle's concerns in his ruling, in language quoted by CryptoTimes from the arbitration filings: "Circle became appropriately concerned that Heka arbitrage was structured and possibly encouraged by Tether so that US dollars could be moved to Tether from Circle in exchange for USDC."

Heka rejected the framing. A spokesperson said the fund "never engaged in market manipulation and has never been the subject of any regulatory investigation or proceeding involving market manipulation or similar misconduct." The spokesperson also characterised Circle's push to make the arbitration documents public as "a transparent attempt to distract others from the real issue: its refusal to honor its promise to redeem USDC for cash." Tether has not issued a public statement on the matter.

Stablecoin Market Context

The case lands at a moment of intensifying competition between the two largest stablecoins. USDT holds a market cap of roughly $190 billion as of July 2026 but accounts for only about 25 percent of adjusted transaction volume. USDC stands at around $75 billion in market cap, a figure that represents approximately 73 percent growth year-over-year, and has captured approximately 70 percent of adjusted transaction volume in the first half of 2026. Total stablecoin transaction volume reached a record $1.79 trillion in June 2026 alone, up 63 percent from the prior month, according to CoinDesk data.

Circle's decision to file in federal court, rather than quietly accept its arbitration win, is being read by analysts as a calculated move. Making the documents public amplifies reputational pressure on Tether at a time when regulatory scrutiny of stablecoins is rising globally.

Why This Matters Outside the United States

USDT on the Tron network functions as everyday financial infrastructure across Nigeria, Ghana, Kenya, and Southeast Asian remittance corridors, as well as South Asian markets including Pakistan and India. Users in these markets rely on it for savings, peer-to-peer trading, and cross-border transfers where local currencies are volatile. The arbitration record suggests that Tether's interventions in stablecoin markets may be driven by competitive strategy rather than neutral market participation.

The stakes are higher given Tether's May 2026 investment in LemFi, a cross-border payment platform targeting African and Asian diaspora remittance corridors from the UK, US, and Canada. If regulators in markets where stablecoin policy is still being formed, including India, Nigeria, and South Africa, treat the arbitration findings as evidence of aggressive competitive conduct, USDT-dependent users and fintech developers could face policy disruption.

USDC is also expanding its institutional footprint in these regions. According to CoinDesk, Standard Chartered and BNY have launched USDC-based services, and Standard Chartered operates extensively across South Asia and sub-Saharan Africa. If institutional rails for USDC widen, retail adoption in markets currently dominated by USDT may follow, particularly if Tether's reputational exposure continues to grow.

The Boston court's confirmation of the arbitration award is the next formal step.