Tether Engages Big Four Firm for First Full Independent Audit, Billing It as Largest Inaugural Audit in Financial History

Tether, the issuer of USDT and the dominant force in the global stablecoin market, announced on March 24, 2026 that it has formally engaged an unnamed Big Four accounting firm to conduct a full independent financial statement audit, the first in its history [1]. The company describes the undertaking as "the biggest ever inaugural audit in the history of financial markets," citing USDT's $184 billion market capitalization and a global user base exceeding 550 million [1].

A Step Beyond Attestations

For years, Tether's approach to financial transparency consisted of quarterly attestations, a form of limited-scope review that verifies a specific set of figures at a point in time but falls well short of the comprehensive examination that a full financial statement audit entails [2]. Attestations remain the standard practice across all stablecoin issuers today; Tether's move to a full audit is a deliberate step beyond that industry benchmark [1]. The audit will provide full visibility into the composition and quality of Tether's reserves, encompassing a uniquely complex mix of digital assets, traditional reserves, and tokenised liabilities that the company says is rarely seen outside the world's largest sovereign institutions [1].

The initial onboarding phase of the engagement concluded several weeks before the public announcement, during which the auditing firm conducted a comprehensive assessment of Tether's internal controls, financial reporting systems, and a broad range of stakeholder relationships [1]. The selection process was competitive, drawing interest from several audit firms.

"The Big Four Firm was selected through a competitive process because the organisation is already operating at Big Four audit standard; the audit will be delivered."

Simon McWilliams, Chief Financial Officer, Tether [1]

Simon McWilliams, who joined Tether as Chief Financial Officer in early 2025, has been identified as central to preparing the company's internal systems for the rigour of a full audit. His appointment marked a deliberate shift in governance infrastructure, aimed at aligning Tether's operations with the standards expected of a globally significant financial institution.

Scale and Market Context

Tether controls approximately 60% of the stablecoin market by volume, a position that gives USDT outsized systemic importance across cryptocurrency exchanges, DeFi protocols, and international payment corridors [2]. Its nearest competitor, Circle's USDC, holds the second-largest position and has long been subject to annual audits conducted by Deloitte, in addition to monthly attestations [3]. Tether's audit announcement directly narrows a credibility gap that has historically differentiated the two issuers in institutional and regulatory conversations.

The announcement came on the same day Circle's stock dropped sharply, though analysts attributed that decline primarily to proposed U.S. legislation that could restrict stablecoin issuers from offering yield to holders, rather than to Tether's announcement directly [3].

Metric	Figure
USDT market capitalization	$184 billion
Tether stablecoin market share	approximately 60%
Tether global user base	550 million+
Audit type (prior)	Quarterly attestations only
Audit type (new)	Full independent financial statement audit
CFO appointment	Simon McWilliams, early 2025
Audit firm	Unnamed Big Four (Deloitte, EY, KPMG, or PwC)

Years of Work Toward Scrutiny

CEO Paolo Ardoino framed the audit as the product of sustained internal investment rather than a reactive response to external pressure.

"Tether's mission has always been to build trust through action, not promises. Trust is built when institutions are willing to open themselves fully to scrutiny. This audit represents years of work to strengthen our systems so that Tether can meet the highest standards applied in global finance."

Paolo Ardoino, CEO, Tether [1]

Ardoino added that for the hundreds of millions of people and businesses relying on USDT daily, the audit is not a compliance formality but a statement of accountability and resilience in the infrastructure underpinning the digital dollar.

The significance of that framing is sharpened considerably by Tether's regulatory history. In 2021, the Commodity Futures Trading Commission fined Tether $41 million for falsely claiming that its stablecoins were fully backed by fiat currency [2]. That same year, Tether reached a settlement with the New York Attorney General's office after regulators alleged the company had covered up approximately $850 million in losses [2]. In 2024, the Department of Justice was reported to be investigating Tether for potential violations of anti-money-laundering and sanctions rules [2].

Tether Transparency Timeline

Date	Event
2021	$41M CFTC fine for misrepresenting reserve backing
2021	NY AG settlement over approximately $850M in covered-up losses
2024	DOJ investigation into AML and sanctions violations reported
Early 2025	CFO Simon McWilliams appointed to prepare for full audit
March 24, 2026	Formal Big Four audit engagement announced publicly

The audit announcement lands at a moment of elevated regulatory attention on stablecoins in the United States, with bipartisan stablecoin legislation advancing in Congress and the Trump administration taking a markedly more permissive posture toward digital asset companies than its predecessor [2]. Tether has also recently launched USAT, a U.S.-dollar stablecoin designed for compliance with anticipated domestic regulatory frameworks [2].

The identity of the Big Four firm has not been disclosed. Once the audit is completed and published, it will represent the first time the market has access to a fully audited financial statement from the world's largest stablecoin issuer, a development that market participants, regulators, and institutional counterparties have sought for nearly a decade.