JPMorgan Chase & Co., the largest U.S. bank by assets and the top investment bank by fees, is questioning the so-called universal bank model's future, Bloomberg News reported yesterday. Top-tier investment banks are "uninvestable at this point with a risk of spinoff from universal banks," JPMorgan analysts led by London-based Kian Abouhossein wrote in a research note today. They cited potential rule changes and curbs on capital and funding.