(Bloomberg) -- A cyberattack against a division of UnitedHealth Group Inc. has caused a nationwide outage of a computer network that’s used to transmit data between health-care providers and insurance companies, rendering some pharmacies unable to process prescriptions, according to the company and reports from affected organizations. Most Read from BloombergNvidia Rises Most in About Nine Months as AI Drives SalesT-Bills Without Tax Bills? This Fund Says It Cracked the CodeStocks Rally as AI Cr