Complex sentence: The Alexis de Tocqueville Institution (not institute; abbreviated AdTI) is a Washington, D.C.-based commercial think-tank and consultancy that produces reports at the behest of its sponsors.
Split into simpler sentences: The Alexis de Tocqueville Institution (AdTI) (not "Institute") is a Washington, DC-based commercial think-tank and consultancy. It produces reports at the behest of its sponsors.