It is a concept launched by Securities Exchange Board of India. Anchor investors are institutional investors who are invited to subscribe the shares before the Initial Public Offers (IPOs) opens up so that it jazzes up the popularity of its issue. They are required to take up the share at a fixed price to make other investors confident and improve the demand of the share.
Each anchor investor needs to invest a minimum of 10 crore Rupees in the issue.
Management site 