The FTSE 100 opened lower on Monday, joining a broader European sell-off sparked by U.S. President Donald Trump's warning of potential sanctions against nations resisting his push to acquire Greenland. The blue-chip index fell 0.1% by 0829 GMT, with Germany's DAX and France's CAC 40 dropping over 1%. The British pound edged up slightly against the dollar.

Geopolitical anxiety overshadowed a slate of corporate earnings reports. Marshalls reported £43.6 million in full-year profit, matching estimates, while Ashtead Technology saw revenue jump 21% to £203 million. Dowlais Group raised its guidance, expecting adjusted revenue of about £5 billion. Big Technologies stock surged 16% after settling a £38.5 million litigation case.

Investors are weighing the fallout from Trump's tariff threats, which have already sent gold to record highs. The market reaction underscores how geopolitical shocks can quickly override company-specific news. Attention now turns to further U.S. policy signals and their potential impact on global trade flows and currency markets.