Tether hires a Big Four firm for the first full financial audit of $184b USDT reserves, aiming to reset stablecoin transparency and institutional trust.

Tether, the issuer of the world’s largest stablecoin by market capitalization, announced on March 24 that it has entered a formal engagement with a Big Four accounting firm to complete its first-ever full independent financial statement audit — a move company leadership describes as the biggest inaugural audit in the history of financial markets.

The announcement marks a turning point for Tether, which has long faced scrutiny over its reserve transparency. USDT currently circulates at a market cap exceeding $184 billion, underpinning a global user base of more than 550 million people. Despite publishing quarterly attestations through BDO Italy in recent years, critics and institutional investors have consistently demanded a more rigorous, comprehensive audit — one that only the Big Four tier of accounting firms can credibly deliver.

Tether’s Decade of Scrutiny

Questions about whether each USDT token is truly backed 1:1 by dollar-denominated reserves have followed Tether since the stablecoin’s launch in 2014. The collapse of multiple major exchanges and lending platforms between 2022 and 2024 heightened calls for deeper accountability. Attestations, while standard practice across the stablecoin sector, fall well short of the full scope and independence of a financial statement audit. Tether’s own press release acknowledged this gap directly, noting that “while others in the industry have settled for the minimum viable level of transparency, Tether is building the architecture against which the next generation of global financial standards will be measured.”

Tether’s path to this engagement was deliberate. The appointment of Simon McWilliams as Chief Financial Officer in early 2025 was specifically intended to build the internal financial architecture required to meet Big Four standards. According to McWilliams, the selection process was competitive. “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,” he said in the company’s official statement.

CEO Paolo Ardoino framed the decision in terms of accountability to Tether’s global user base. “Trust is built when institutions are willing to open themselves fully to scrutiny,” Ardoino said. “This audit represents years of work to strengthen our systems so that Tether can meet the highest standards applied in global finance. For the hundreds of millions of people and businesses who rely on USD₮ every day, this audit is not just a compliance exercise; it is about accountability, resilience, and confidence in the infrastructure they depend on.”

As part of the audit onboarding, which concluded several weeks ago, the engaged firm conducted a comprehensive assessment of Tether’s systems, internal controls, and financial reporting. Multiple Big Four firms reportedly expressed interest in the engagement — a signal, Tether argues, of the audit’s significance to the broader industry.

Tether also noted it will be moving listed securities over the coming days as part of the reserve optimization process. The ongoing expansion of Tether’s broader portfolio — which includes over 140 investments and a USDT float sitting near $185 billion — means the audit will cover a uniquely complex mix of digital assets, traditional reserves, and tokenized liabilities. The company holds, among other things, 140 tons of gold in a Swiss vault worth approximately $23 billion, and has co-led a $7.5 million financing round in Utexo to build native USDT settlement on the Bitcoin and Lightning networks.

The identity of the specific Big Four firm has not been disclosed. Tether said the full audit will provide “complete visibility into the strength and positioning” of its reserves — and, if completed as described, would represent a watershed moment not just for USDT, but for institutional confidence in the stablecoin sector writ large.