Study to Evaluate The Safety and Efficacy of Balovaptan in Participants With Acute Ischemic Stroke at a High Risk of Developing Malignant Brain Edema

Inclusion Criteria: * Diagnosis of LVO in the anterior circulation such that study drug administration can be initiated within 12 hours of LKW and at risk of MCE development, as defined as follows: * Documented occlusion of terminus ICA and/or MCA on CTA or magnetic resonance angiogram and * ASPECTS score \</=5 on NCCT and * NIHSS \>15 for the non-dominant hemisphere and \>20 for the dominant hemisphere (or \> 20 if dominant/non-dominant hemisphere unknown) * Present with a WUS \</=8 hours from awakening provided the above criteria are met * Participants with a history of seizures on anti-epileptic medications may be included if they have been on stable doses of those medications for at least 12 weeks prior to LKW, they have not experienced seizures during that time frame, and their anti-epileptic medicines are continued during the study * For women of childbearing potential: participants who agree to remain abstinent (refrain from heterosexual intercourse) or use contraception and agree to refrain from donating eggs * No specific contraception methods for males are required. Exclusion Criteria: * Participants who are \>12 hours from LKW at the start of treatment with study drug or \>8 hours from awakening with WUS * Any MLS on brain imaging * Evidence of intracranial hemorrhage at screening based on NCCT * Contraindication to MRI examination * Evidence of additional anterior cerebral artery (ACA) infarction * Diagnosis of brain death * Planned surgical decompression prior to randomization * Participants with a known history of a hereditary bleeding disorder which increases bleeding risk * Chronic kidney disease stage III or higher * Hepatic injury * Diagnosis of diabetes insipidus * Participants who have received any prophylactic hyperosmolar therapy * Participants who have received treatment with any other V1a and/or V2 receptor-blocking agent or glyburide * A preexisting medical condition for which the participant is unlikely to survive the next 6 months * Planned limitation or withdrawal of life-sustaining treatment during hospital admission * Participants who are pregnant or breastfeeding, or intending to become pregnant