Group Group one is targeting high-revenue companies with Ryuk file-encrypting malware. One victim received $34 million from one victim in exchange for the decryption key that unlocked their computers. The average payment received by this particular group is 48 bitcoins (close to $750,000), and they made at least $150 million since 2018. Ryuk group one is highly proficient at moving laterally inside a compromised network and erasing as much of their tracks as possible.
Source: https://www.bleepingcomputer.com/news/security/how-ryuk-ransomware-operators-made-34-million-from-one-victim/