Inclusion Criteria:  Patients presenting with posterior circulation ischemic stroke symptoms due to partial or complete basilar artery occlusion within 24 hours from symptom onset (or clinical deterioration/coma) or the time the patient was last known to be well. Patient's age is ≥18 years Presence of basilar artery occlusion, proven by CT Angiography or MR Angiography. Basilar artery occlusion is defined as 'potentially retrievable' occlusion at the basilar artery. This can be a partial or complete occlusion. Premorbid mRS ≤3 (independent function or requiring only minor domestic assistance and able to manage alone for at least 1 week). Local legal requirements for consent have been satisfied.  Exclusion Criteria:  Intracerebral hemorrhage (ICH) or other diagnosis (e.g. tumour) identified by baseline imaging. Posterior circulation Acute Stroke Prognosis Early CT score (pc-ASPECTS) <7 on non-contrast CT, CT Angiography source images or DWI MRI. Significant cerebellar mass effect or acute hydrocephalus. Established frank hypodensity on non-contrast CT indicating subacute infarction. Bilateral extensive brainstem ischemia. Strong suspicion of underlying intracranial atherosclerotic disease (e.g diffuse arterial calcifications, basilar stenosis) or suspected dissection requiring immediate neuro-interventional procedure likely to involve intracranial stenting. Pre-stroke mRS of ≥4 (indicating moderate to severe previous disability). Other standard contraindications to intravenous thrombolysis. Contraindication to imaging with contrast agents. Clinically evident pregnant women. Current participation in another research drug treatment protocol. Known terminal illness such that the patients would not be expected to survive a year. Planned withdrawal of care or comfort care measures. Any condition that, in the judgment of the investigator could impose hazards to the patient if study therapy is initiated or affect the participation of the patient in the study.