Rising geopolitical tensions between the United States and Iran contributed to Brent crude oil prices climbing above $100 a barrel on Friday, marking the first time since May that the benchmark crude has reached this level. The escalation in Middle Eastern tensions has renewed concerns over global oil supply stability.

In London, the FTSE 100 index closed down 77.8 points, or 0.73 percent, at 10,639.17. Despite the broader market decline, shares of major oil companies saw gains. BP’s stock rose 16.6 pence, or 3.1 percent, to 556 pence, while Shell’s shares increased by 52 pence, or 1.6 percent, closing at £33.44. These gains partially mitigated the impact of broader market weakness on the index.

Among other notable movements on the FTSE 100, Segro led the gains, climbing 58.25 pence, or 6.5 percent, to 953 pence. The industrial property group’s shares surged after its board indicated it was inclined to back a “best and final” takeover bid worth £14 billion from US rival Prologis. The offer values Segro at £10.32 per share and reflects a protracted acquisition process.

Conversely, Centrica, the owner of British Gas, experienced the largest decline on the FTSE 100. The stock fell 18.5 pence, or 10.2 percent, to 161.5 pence following the release of its half-year financial results, which showed a decrease in both operating profit and revenue for the first half of 2026.

The FTSE 250 index also recorded losses, falling 299.30 points, or 1.3 percent, to close at 23,627.33. Market sentiment appeared subdued amid ongoing geopolitical uncertainty and mixed corporate earnings reports.

The renewed volatility in oil markets, driven by concerns over US-Iran relations, underscores the sensitive balance between geopolitical risk and energy supply. Investors continue to monitor developments closely, given their potential impact on global economic stability and inflationary pressures.