Berkshire Hathaway (NYSE: BRK.A)(NYSE: BRK.B) has had a difficult time finding places to put its money to work in recent years, and this has led to the company branching out into more tech-focused investments. One area that is a natural fit for Buffett and his team is financial technology, or fintech. Banking has long been a favorite industry of Buffett's, and that's obvious in the company's massive stock portfolio -- in fact, Bank of America (NYSE: BAC) is Berkshire's second-largest investment. So, when looking to branch out into newer technologies, the financial sector certainly makes sense. We've already seen fintech investments from Berkshire such as Brazilian payment processor StoneCo (NASDAQ: STNE) and India-based mobile payments company Paytm, and we just learned that another has been added. Image source: Getty Images. Berkshire's latest fintech investment It was reported on Tuesday that Berkshire has invested $500 million in another Brazilian fintech start-up called Nubank, which is best known for issuing credit cards. Nubank, which is private, raised a total of $750 million in new funding (including Berkshire's) at a valuation of $30 billion. Nubank currently has 40 million customers and plans to expand its operations into Mexico and Columbia, and there have previously been rumors that the company is eyeing a U.S. IPO in the not-too-distant future. StoneCo has been a highly successful investment for Berkshire, up by about 160% from the $24 share price Berkshire paid at the time of the fintech's late-2018 IPO, and Berkshire is clearly hoping for a repeat of its initial success in the Brazilian fintech market. 10 stocks we like better than Berkshire Hathaway (B shares)When investing geniuses David and Tom Gardner have a stock tip, it can pay to listen. After all, the newsletter they have run for over a decade, Motley Fool Stock Advisor, has tripled the market.* David and Tom just revealed what they believe are the ten best stocks for investors to buy right now... and Berkshire Hathaway (B shares) wasn't one of them! That's right -- they think these 10 stocks are even better buys. See the 10 stocks *Stock Advisor returns as of June 7, 2021 Bank of America is an advertising partner of The Ascent, a Motley Fool company. Matthew Frankel, CFP owns shares of Bank of America and Berkshire Hathaway (B shares). The Motley Fool owns shares of and recommends Berkshire Hathaway (B shares) and Stoneco LTD. The Motley Fool recommends the following options: long January 2023 $200 calls on Berkshire Hathaway (B shares), short January 2023 $200 puts on Berkshire Hathaway (B shares), and short January 2023 $265 calls on Berkshire Hathaway (B shares). The Motley Fool has a disclosure policy.Source