Buffett-backed Nubank in talks to hire U.S. IPO underwriters -sources

June 21 (Reuters) - Nubank, the Brazilian digital bank backed by Warren Buffett's Berkshire Hathaway, has invited investment banks to pitch for roles on its upcoming initial public offering (IPO) in the United States, people familiar with the matter said on Monday.

Nubank's founder and Chief Executive David Vélez had said as recently as this month that an IPO was likely to happen at some point but was not in the company's plans.

Its discussions with banks illustrate that the preparations for a stock market debut, which one of the sources said could value Nubank at more than $40 billion, are more advanced than previously known.

The IPO could happen by the end of this year or early 2022, two of the sources said. It would be one of the biggest ever stock market debuts of a South American company, putting it on par with other expected high-profile offerings such as of online brokerage Robinhood Markets Inc.

The sources spoke on condition of anonymity because the IPO preparations are confidential. A spokesperson for Nubank, whose legal name is Nu Pagamentos SA, declined to comment. -sources (Reporting by Carolina Mandl in Sao Paulo, David French in New York and Anirban Sen in Bengaluru Editing by Greg Roumeliotis)