UnitedHealth Group has been significantly impacted by a ransomware attack on its subsidiary, Change Healthcare, which has disrupted parts of the U.S. healthcare system. The attack, which occurred in February, has resulted in substantial financial losses for UnitedHealth, with costs expected to exceed $1 billion and a financial impact of $872 million in Q1, representing 0.87% of its Q1 revenue. The breach compromised sensitive health information and led to widespread operational disruptions, including delayed payments to healthcare providers. In response to the crisis, UnitedHealth CEO Andrew Witty is scheduled to testify before a U.S. House subcommittee, although UnitedHealth did not send a representative to the initial federal hearing. The company has faced criticism for its handling of the attack, including its decision to pay a ransom to the attackers.