v3.25.2
Fair values of financial instruments carried at fair value - Financial instruments measured at fair value using a valuation technique with significant unobservable inputs - Level 3 (Details) - Recurring fair value measurements - GBP (£)
£ in Millions
Jun. 30, 2025
Dec. 31, 2024
Jun. 30, 2024
Dec. 31, 2023
Trading liabilities        
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]        
Financial liabilities £ 39,542 £ 42,633    
Designated at fair value        
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]        
Financial liabilities 39,964 37,443    
Derivatives        
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]        
Financial liabilities 176,367 197,082    
Financial investments        
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]        
Financial assets 41,097 39,990    
Trading assets        
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]        
Financial assets 114,445 116,042    
Designated and otherwise mandatorily measured at fair value through profit or loss        
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]        
Financial assets 9,097 9,417    
Derivatives        
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]        
Financial assets 176,838 198,172    
Level 3        
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]        
Financial assets 6,091 7,613    
Financial liabilities 5,847 5,941    
Level 3 | Private equity including strategic investments        
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]        
Financial liabilities 1 1    
Level 3 | Asset-backed securities        
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]        
Financial liabilities 0 0    
Level 3 | Structured notes        
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]        
Financial liabilities 3,036 2,958    
Level 3 | Derivatives        
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]        
Financial liabilities 2,775 2,355    
Level 3 | Other portfolios        
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]        
Financial liabilities 35 627    
Level 3 | Trading liabilities        
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]        
Financial liabilities 34 624 £ 102 £ 252
Level 3 | Trading liabilities | Private equity including strategic investments        
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]        
Financial liabilities 0 0    
Level 3 | Trading liabilities | Asset-backed securities        
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]        
Financial liabilities 0 0    
Level 3 | Trading liabilities | Structured notes        
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]        
Financial liabilities 0 0    
Level 3 | Trading liabilities | Derivatives        
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]        
Financial liabilities 0 0    
Level 3 | Trading liabilities | Other portfolios        
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]        
Financial liabilities 34 624    
Level 3 | Designated at fair value        
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]        
Financial liabilities 3,038 2,962 3,846 3,958
Level 3 | Designated at fair value | Private equity including strategic investments        
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]        
Financial liabilities 1 1    
Level 3 | Designated at fair value | Asset-backed securities        
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]        
Financial liabilities 0 0    
Level 3 | Designated at fair value | Structured notes        
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]        
Financial liabilities 3,036 2,958    
Level 3 | Designated at fair value | Derivatives        
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]        
Financial liabilities 0 0    
Level 3 | Designated at fair value | Other portfolios        
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]        
Financial liabilities 1 3    
Level 3 | Derivatives        
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]        
Financial liabilities 2,775 2,355 2,956 2,335
Level 3 | Derivatives | Private equity including strategic investments        
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]        
Financial liabilities 0 0    
Level 3 | Derivatives | Asset-backed securities        
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]        
Financial liabilities 0 0    
Level 3 | Derivatives | Structured notes        
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]        
Financial liabilities 0 0    
Level 3 | Derivatives | Derivatives        
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]        
Financial liabilities 2,775 2,355    
Level 3 | Derivatives | Other portfolios        
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]        
Financial liabilities 0 0    
Level 3 | Private equity including strategic investments        
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]        
Financial assets 1,206 1,178    
Level 3 | Asset-backed securities        
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]        
Financial assets 169 213    
Level 3 | Structured notes        
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]        
Financial assets 0 0    
Level 3 | Derivatives        
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]        
Financial assets 2,269 1,882    
Level 3 | Other portfolios        
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]        
Financial assets 2,447 4,340    
Level 3 | Financial investments        
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]        
Financial assets 182 1,079 788 907
Level 3 | Financial investments | Private equity including strategic investments        
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]        
Financial assets 114 108    
Level 3 | Financial investments | Asset-backed securities        
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]        
Financial assets 50 68    
Level 3 | Financial investments | Structured notes        
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]        
Financial assets 0 0    
Level 3 | Financial investments | Derivatives        
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]        
Financial assets 0 0    
Level 3 | Financial investments | Other portfolios        
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]        
Financial assets 18 903    
Level 3 | Trading assets        
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]        
Financial assets 2,535 3,570 2,102 2,050
Level 3 | Trading assets | Private equity including strategic investments        
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]        
Financial assets 1 1    
Level 3 | Trading assets | Asset-backed securities        
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]        
Financial assets 119 145    
Level 3 | Trading assets | Structured notes        
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]        
Financial assets 0 0    
Level 3 | Trading assets | Derivatives        
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]        
Financial assets 0 0    
Level 3 | Trading assets | Other portfolios        
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]        
Financial assets 2,415 3,424    
Level 3 | Designated and otherwise mandatorily measured at fair value through profit or loss        
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]        
Financial assets 1,105 1,082 3,214 2,882
Level 3 | Designated and otherwise mandatorily measured at fair value through profit or loss | Private equity including strategic investments        
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]        
Financial assets 1,091 1,069    
Level 3 | Designated and otherwise mandatorily measured at fair value through profit or loss | Asset-backed securities        
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]        
Financial assets 0 0    
Level 3 | Designated and otherwise mandatorily measured at fair value through profit or loss | Structured notes        
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]        
Financial assets 0 0    
Level 3 | Designated and otherwise mandatorily measured at fair value through profit or loss | Derivatives        
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]        
Financial assets 0 0    
Level 3 | Designated and otherwise mandatorily measured at fair value through profit or loss | Other portfolios        
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]        
Financial assets 14 13    
Level 3 | Derivatives        
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]        
Financial assets 2,269 1,882 £ 2,496 £ 1,823
Level 3 | Derivatives | Private equity including strategic investments        
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]        
Financial assets 0 0    
Level 3 | Derivatives | Asset-backed securities        
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]        
Financial assets 0 0    
Level 3 | Derivatives | Structured notes        
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]        
Financial assets 0 0    
Level 3 | Derivatives | Derivatives        
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]        
Financial assets 2,269 1,882    
Level 3 | Derivatives | Other portfolios        
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]        
Financial assets £ 0 £ 0