Nu Holdings Ltd., the Brazilian digital bank that has been battling incumbent lenders for the past decade, surpassed Itau Unibanco Holding SA as the most-valuable financial institution in Latin America.The stock of Nubank, as the firm is known, closed 3.8% higher on Tuesday. That boosted its market capitalization to $58.2 billion, putting it just ahead of Itau, which stood at about $56 billion....