AstraZeneca's US listing creates £200 mn UK stamp‑duty gap

When AstraZeneca Plc disclosed its “triple‑listing” plan on 29 September 2025, market watchers in London, New York and Stockholm were instantly on alert.

The British‑Swedish drugmaker said it would harmonise share trading across three exchanges – the New York Stock Exchange (NYE), the London Stock Exchange (LSE) and Nasdaq Stockholm. The crux? Depositary Interests (DIs) that sit on the NYE would be exempt from the United Kingdom’s 0.5 % stamp‑duty reserve tax, a move that Treasury officials estimate will shave roughly £200 million off annual revenue.

Why the move matters

At a market capitalisation of £172 billion (about $231 billion at today’s rates), AstraZeneca sits in the top ten of the FTSE 100 Index. Retaining that slot means passive funds that track the index – for example BlackRock’s iShares Core FTSE 100 UCITS ETF – continue to hold the shares automatically. But the real payoff is expected to come from U.S. institutional money, which historically favours the liquidity of NYE‑listed securities.

How the new structure works

Depositary Interests are essentially wrappers issued by a depositary bank that represent ownership of foreign‑company shares. In this case, investors buying the DI on the NYE will own a claim on the underlying AstraZeneca stock without physically holding the London‑listed certificate. Because the DI is technically a foreign‑security, the UK stamp‑duty reserve tax – which normally hits every share purchase on the LSE – does not apply.

The plan still requires green lights from three regulators: the U.S. Securities and Exchange Commission, the Financial Conduct Authority and Sweden’s Finansinspektionen. All three have signalled that they will review the proposal within the next few months, a timeline that historically stretches between six and twelve months before a structural change can be implemented.

Financial impact on the UK Treasury

According to the Financial Times, the exemption will create a £200 million shortfall for His Majesty's Treasury. That loss represents roughly 2.44 % of the £8.2 billion total stamp‑duty and reserve‑tax haul recorded in the 2024‑2025 fiscal year. While the figure sounds dramatic, Treasury analysts note that the broader budget impact is modest – the hole can be offset by modest adjustments elsewhere, but it does highlight the erosion of the UK’s primary‑listing appeal.

Reactions from investors and regulators

Large U.S. asset managers such as BlackRock Inc. and Vanguard Group welcomed the move, citing the “greater accessibility for American institutional investors”. A senior analyst at J.P. Morgan Chase & Co. told Bloomberg that the structure “offers a tidy way to tap the deep U.S. pool without fully abandoning the London base”.

Critics, however, argue that the maneuver underlines how “feeble Britain’s fundraising ability has become”, a line lifted straight from a Bloomberg Opinion column. The piece warned that if the LSE’s role shrinks to merely a price‑discovery venue for a handful of dual‑listed giants, the market could become a “secondary playground” for a few multinational behemoths.

What this signals for London’s listing market

Since the United Kingdom’s departure from the EU on 31 January 2020, the LSE has seen a gradual decline in fresh primary listings. As of September 2025, the total market capitalisation of the FTSE 100 sits around £2 trillion, with AstraZeneca alone accounting for about 8.6 % of that value. The company’s decision to keep its FTSE 100 slot while effectively becoming a U.S.‑listed entity could set a template for other large British firms seeking to broaden their investor base without shedding their home‑market identity.

In practice, the “triple‑listing” could encourage a wave of similar arrangements, especially among firms that already have a sizable global footprint and a dual‑headquarters set‑up. Yet regulators in London remain cautious; the FCA has hinted that any future exemptions to stamp‑duty will be examined on a case‑by‑case basis to prevent a race‑to‑the‑bottom.

For now, AstraZeneca’s shareholders get a taste of the “nifty financial acrobatics” Bloomberg described, while the UK Treasury watches the £200 million hole grow – a reminder that even the world’s biggest drugmakers can reshape the rules of the game with a well‑timed filing.