Rickard Oste and his brother Bjorn Oste have become multi-millionaires after their Swedish oat milk company Oatly raised $1.4 billion in its IPO. The brothers' combined stake was worth $448 million after the shares were priced $17, according to Bloomberg Billionaires Index. Oatly, which counts Oprah Winfrey, Natalie Portman and Jay Z as investors, is now valued at $10 billion.