June 28 (Reuters) - Ventas Inc said on Monday it would buy New Senior Investment Group in an all-stock transaction valued at about $2.3 billion to help the healthcare-focused real estate investment trust expand into the senior housing market.

New Senior shareholders will receive 0.1561 shares of newly issued Ventas stock for every share of New Senior common stock. That implies a value of $9.10 per New Senior share, a premium of 31.7%.

The deal, which includes $1.5 billion of debt, is expected to close during the second half of 2021.

Ventas, which owns or has investments in about 1,200 properties, expects the deal to expand its stake in the senior housing industry that is likely to grow significantly and recover from the trough of COVID-19.

Ventas expects to realize between $16 to $18 million in annualized corporate synergies from the transaction from 2022.

Centerview Partners LLC is the financial adviser to Ventas on the deal, while Morgan Stanley & Co is New Senior's adviser. (Reporting by Manas Mishra and Mrinalika Roy in Bengaluru; Editing by Maju Samuel)