Complex sentence: Dresdner Kleinwort was a British-based investment bank: it disappeared as a brand from the world of investment banking in September 2009, when its remaining businesses adopted the Commerzbank branding.
Split into simpler sentences: Dresdner Kleinwort was a British-based investment bank. It disappeared as a brand from the world of investment banking in September 2009, when its remaining businesses adopted the Commerzbank branding.