Barclays dropped 3% to £424.95, Lloyds Banking Group fell 2% to £98, and HSBC retreated by £29.6 to £1,302.4.
The sector came under pressure as rising oil prices raised concerns around inflation and dampened risk appetite.
Mining shares also weakened amid overall market uncertainty. Antofagasta slid 3.44% to £4,015, while Fresnillo fell 3.20% to £3,988.
Meanwhile, Intertek tumbled 9.11% to £4,310. AstraZeneca also edged lower, slipping 0.87% to £15,120.