May 22 (Reuters) - Sanofi will acquire Vigil Neuroscience, a clinical-stage biotech company in a $470 million deal, the companies said on Thursday, as the French drugmaker seeks to boost its neurological pipeline through an Alzheimer's drug.

Vigil Neuroscience shares soared 242% in morning trading.

Sanofi would pay $8 per share to Vigil shareholders, who would also be eligible for a contingent value right (CVR) of $2 per share, the statements added. The CVR is tied to a drug that Vigil is developing for the potential treatment of Alzheimer's disease.

A CVR is a right given to a company's stockholders during a merger, entitling them to additional benefits after the closing, either in the form of cash, stock or both, when certain payment conditions are met.

Earlier this month, Sanofi revealed plans to invest at least $20 billion in the United States through 2030 to boost manufacturing and research, through direct investments in Sanofi sites and partnerships with other domestic manufacturers.

The companies are expected to close the transaction in the third quarter of 2025. Sanofi said the transaction will not affect its 2025 financial outlook.

The acquisition would give Sanofi, one of the world's largest vaccine makers, control over Vigil's VG-3927, an oral drug being prepared for a potential treatment in Alzheimer's.

In June 2024, Sanofi made a $40 million equity investment in Vigil, which included an exclusive negotiation right for the drug.

Vigil's monoclonal antibody program, VGL101, would not be acquired by Sanofi and would return to U.S. drugmaker Amgen, Vigil said.