The threat that AstraZeneca – the UK’s largest public company, with a market cap of GBP 160.7bn – could abandon its London listing is sure to worry UK financiers and regulators.

Which is entirely the point.

There are few better ways for a UK-listed corporate to kick up a stink than to threaten to delist from the London Stock Exchange.

The UK’s venerable bourse has operated under a cloud for several years, with lower IPO volumes and a spate of delistings reducing its aggregate market cap to ninth place in the global rankings, although this does include Euronext, which spans several European exchanges.

Word that AstraZeneca’s CEO Sir Pascal Soriot “would like to move the stock market listing to the United States” and had even considered redomiciling, as reported by The Times on Tuesday 1 July, elided the fact that the pharma giant’s shares do already trade on the Nasdaq, albeit via an ADR programme.

The intervention met with investor approval, with the shares climbing 2.8% yesterday. But it also carried with it the whiff of gunpowder – a shot fired across the UK government’s bow. Following a series of run-ins with the Labour administration, any prospective capital markets move may be only a secondary concern, if you’ll pardon the pun.

Yesterday’s article pointed to Soriot being “deeply frustrated” with the operating environment in the UK, particularly medicine approvals and pricing.

Last year, UK drug regulator NICE rejected AstraZeneca’s breast cancer drug Enhertu for rollout across the NHS England public health system on cost-effectiveness grounds – this despite Health Secretary Wes Streeting being lobbied by cancer charities and the treatment being available in 22 other European territories, including Scotland.

In February 2025, AstraZeneca dropped a planned GBP 450m investment at its Speke, Merseyside plant in the UK, amid a surprisingly public spat with ministers over the amount of accompanying government cash that had been promised.

“Soriot’s flying a kite,” one veteran capital markets lawyer argued. Gripes with the UK government over drug approvals or public grants would be unaffected by listing location.

Amid dismal polling for Labour and a humiliating, protracted u-turn on benefit cuts in parliament over the past week, “the government is probably more susceptible to pressure than at any point,” the lawyer added.

The key question for AstraZeneca’s board is whether readier access to the US’s deeper pool of capital, alongside index reweighting – netted off by the loss of its leading position in the FTSE 100 – would outweigh the political pressure and reputational risk of abandoning the London listing, the lawyer argued.

AstraZeneca moved its ADR programme to the Nasdaq from the NYSE in 2020 and is already a Nasdaq-100 constituent. But its weighting in that index is trimmed by its ADR status as “for inclusion purposes, the market capitalization of an ADR will normally be determined based on the depositary shares outstanding”.

In its 2024 annual report, ADR issuance represented 19.2% of AstraZeneca’s issued share capital.

It currently accounts for between 0.24% and 0.25% of the Nasdaq-100, according to portfolio disclosures by relevant ETFs.

Should AstraZeneca move fully to New York, it would move into the teens in terms of Nasdaq-100 weighting.

But it would still shift from being the biggest fish in its own pond to a relative minnow compared to the trillion-dollar technology giants that dominate that benchmark.

Amid regular complaints that US stocks enjoy higher valuations than their London-listed counterparts, could AstraZeneca at least expect a re-rating?

That seems far from clear cut, with AstraZeneca valued at 12x forecast 2025 EBITDA*, roughly in line with NYSE and Nasdaq-listed pharma peers after factoring differing growth rates, according to analysis by this news service.

Pfizer, which is expected to grow EBITDA more slowly than AstraZeneca over 2025 and 2026, is valued at 8x, while AbbVie, which is growing more quickly, is valued at 14x.

Soriot may well be running the rule on switching FTSE 100 index jockeys for a greater number of Nasdaq-100 passives. Shifting domicile might offer some potential tax advantages, though in a turbulent world these can be legislated away – and make little difference to the operating reality of where a business is most active and cash generative.

But the leak of discussions over a US listing – especially to The Times (London’s historic “paper of record”) – looks more like a canny move by those claiming knowledge of Soriot’s intentions to lean on the UK Department of Health and NICE to play…nice.

A threat to move a listing across the Atlantic is a huge weapon in the arsenal of any company in negotiations with government and regulators, particularly with European governments, so fearful of losing the global race for growth.

In the movie Thirteen Days about 1962’s Cuban Missile Crisis, Secretary of Defense Robert McNamara – played by Dylan Baker – refers to naval action around the island as “not a blockade – this is language, a new vocabulary, the likes of which the world has never seen.”

AstraZeneca perhaps feels it’s pertinent to remind UK regulators that it is willing to use a nuclear option if it doesn’t get its way.

*Data provided by Fidessa and compiled by FactSet. ION Analytics and Fidessa are ION Group companies