A weekly recap of some of the most interesting venture capital deals, funds and start-ups. : Brazilian fintech company StoneCo raised $1.2 billion in its debut on the U.S. public markets this week. Stone is similar to U.S. payments firm Square, facilitating e-commerce both online and in stores through partnerships with card companies and merchants. Jack Ma's Ant Financial and Warren Buffett's Berkshire Hathaway both took large stakes in the company as part of its public offering.