‘Sell in May’ adage breaks down as Trump-era markets reward risk, but not for FTSE 100

IG analysis suggests the old “sell in May” rule has weakened in the Trump era as risk-on conditions have favoured US equities: the S&P 500 has averaged 9.5% gains from May–October during Trump presidencies versus 1.3% in non-Trump years. By contrast the UK 100 (FTSE 100) continues to show a summer lull, reflecting its heavy overseas revenue exposure. IG attributes the divergence to sector composition—US indices are more domestically focused tech beneficiaries—while the FTSE is more exposed to global demand. Traders’ positioning shows complacency on the surface but concentrated risk underneath, with options bets pointing to oil being bid toward $200/barrel by August and rising metal interest amid supply constraints following conflict-driven demand. Overall, the note implies a mixed market impact: stronger seasonal performance for US risk assets, persistent weakness for the FTSE, and elevated commodity-driven tail risks.