Forter, a company that uses machine learning to detect and prevent fraud in online retail transactions, announced today that it has raised $50 million in a series D funding round led by March Capital Partners, bringing its total financing to $100 million. Salesforce Ventures joined the round, along with previous investors including Sequoia Capital and New Enterprise Associates (NEA). Global online retail sales amounted to more than $2 trillion in 2017, and this number is projected to reach more than $4.5 billion by 2021. But as online retail grows, so does online fraud. Account takeover attacks are on the rise, as are high-volume automated "bot" attacks and so-called policy attacks like coupon abuse.