BANGALORE/SAO PAULO, Aug 25 (Reuters) - Brazilian fintech Nubank is seeking a valuation in its planned U.S. initial public offering exceeding that of the country"s top traditional lender Itau Unibanco Holding SA (ITUB4.SA) , two sources familiar with the matter said. If Nubank is successfully listed at greater than Itau"s $55.4 billion market cap, it would be vaulted into the ranks of the world"s largest fintechs, ahead of recently listed Robinhood Markets Inc, for example. One source added that in recent weeks Nubank"s bankers have pitched a valuation of as much as $100 billion, adding that the Brazilian fintech unicorn was unlikely to be valued so highly at the time it goes public. In a recent funding round led by Warren Buffett"s Berkshire Hathaway Inc (BRKa.N), Nubank, which has 40 million clients in Latin America, was valued at $30 billion. According to a ranking by CBInsights, Nubank is the seventh most valuable unicorn worldwide, behind fintechs Stripe, Klarna and Revolut. Nubank has hired investment banking units of Morgan Stanley, Goldman Sachs and Citigroup to help lead its United States.