Companies merger and get acquired due to many strategic business reasons.
The merger is when two companies unite themselves and become a single larger company. Here the process includes a complete combination of two companies through the transfer of ownership. Also, primarily it involves a stock swap or a cash payment.

Most importantly, the boards of directors of both companies must have secure approval from the boards of directors of respective companies

Merger takes place due to below main reasons:
Encourage growth,
Achieve competitive advantages,
Growth in market share,
Diversification of products or services
To increase in value,
Economic growth of the business
Replace leadership

For instance, Dena Bank, Vijaya bank merged with Bank of Baroda.