Risks associated with a potential change in UK political leadership are weighing on financial markets. Growing expectations of a challenge to current Prime Minister Keir Starmer from within the Labour Party have pushed sterling to near one-month lows and the yield on 10-year UK government bonds above 5%. Investors are repricing UK assets, with core concerns centered on a potential loosening of fiscal discipline.
On Friday, Andy Burnham, the Mayor of Greater Manchester, secured eligibility for a by-election in the Makefield constituency, clearing a procedural hurdle in a potential bid for the premiership. Starmer's camp had previously blocked his candidacy in January. This path to a by-election has opened just as the Labour Party faces significant local election losses and Starmer is under pressure to resign, prompting an immediate market reaction. Data shows the pound fell 0.3% against the dollar to 1.3363, extending its recent weekly decline, while the 10-year gilt yield rose over 1 basis point to 5.137%, placing it among the highest in the G7.
Investors widely fear that a Burnham-led government could push policies "leftward"—meaning increased government spending, relaxed fiscal discipline, and higher public borrowing—potentially breaking the current government's framework of fiscal restraint. Paul Markham, Global Head of Equities at GAM, described this as a "toxic combination": rising bond yields coupled with a weakening pound is a typical price signal of questioned fiscal credibility, more commonly seen in emerging markets than developed economies.
The Burnham Effect: Markets Reprice UK Fiscal Credibility A series of statements from Burnham have been the direct trigger for market anxiety. Last year, he publicly accused the UK government of being "held hostage by the bond markets." Last week, he suggested that defense spending should be accounted for separately from fiscal rules, further fueling expectations that his administration could significantly increase gilt issuance. Although he partially walked back his tough rhetoric on bond markets in February, stating that markets "should not be ignored," analysts at Deutsche Bank believe this is insufficient to quell market concerns.
Prediction market Polymarket shows Burnham has become the frontrunner to be the next UK Prime Minister, with a 42% probability, far above the 27% chance of Starmer retaining his position. Polling data also indicates 61% of Labour Party members support Burnham, compared to only 28% for Starmer.
Elias Haddad, Global Head of Market Strategy & FX at BBH, stated that a Labour government led by Burnham would likely bring more spending and borrowing. With the UK's current nominal GDP growth already below the 10-year gilt yield, reining in debt growth becomes increasingly difficult. He judges that "UK fiscal credibility is deteriorating, and the bias for sterling and UK gilts remains to the downside."
Neil Mehta, Macro Portfolio Manager at RBC BlueBay, added that the next Labour leader will likely come from the party's left wing, meaning "UK financial assets and sterling will carry a higher political risk premium for a prolonged period."
Equities Under Pressure, Domestic Assets Bear the Brunt The equity market is also feeling the strain, particularly sectors reliant on domestic policy and the UK economy. A team led by Goldman Sachs strategist Sharon Bell pointed out that under the impact of policy uncertainty, UK domestic banks, domestic equities, and small-cap stocks face the greatest risk, while real estate is especially sensitive to rising yields.
Rich Privorotsky, Head of the One-Delta Trading Desk at Goldman Sachs, noted that markets will naturally begin to consider whether a future leadership change implies a reordering of fiscal priorities, spending plans, and tax policies. The UK gilt market will continue to serve as a crucial "barometer" for testing fiscal credibility.
However, markets have already priced in a significant degree of negative news. The forward price-to-earnings ratio for the FTSE 250 is around 12x, below both its historical absolute and relative averages, and the FTSE 350 trades at a 35% discount to its global peers. Goldman Sachs strategists note that the real estate sector's dividend yield is about 200 basis points higher than the market average, comparable to levels seen during the deep recessions of the early 1990s and the global financial crisis. If gilt yields eventually retreat from their highs, this sector would be a clear beneficiary.
The FTSE 100, supported by its higher weighting in commodities and defensive assets, has outperformed the FTSE 250 year-to-date. However, Goldman Sachs believes this advantage may narrow as tensions with Iran ease; since the ceasefire in early April, the index has largely traded sideways.
Political Uncertainty Resonates with Macro Pressures Political risk is not the only variable facing UK assets. A team led by Davide Silvestrini, a strategist at JPMorgan, pointed out that energy price shocks stemming from the situation in the Strait of Hormuz are combining with domestic UK political uncertainty, creating a "double pressure" on UK assets.
The latest PMI survey data for April shows the UK private sector was hit by a double blow of surging energy costs and weak demand, placing the Bank of England in a more difficult policy position: the energy shock could push inflation higher, while weakening demand poses a downside economic risk. The bond market currently expects the Bank of England to implement two to three rate hikes over the next 12 months, further limiting the potential for yield declines.
Peter Ricketts, a former British diplomat and member of the House of Lords, stated that the domestic political "court drama" will damage the UK's international reputation and influence. He believes that if Starmer is forced to fight for his political survival, his effectiveness in coordinating European responses to the crises in Ukraine and Iran would be significantly diminished. Furthermore, the EU is reluctant to negotiate closer relations with a UK whose prime ministerial candidate remains uncertain.
Russ Mould, Investment Director at AJ Bell, added that the UK is about to get its seventh prime minister in ten years, "not a record any country would be proud of," and this is one reason why UK 10-year gilt yields are among the highest in the G7.
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