The intermediaries (registered with SEBI) involved in an issue, are Merchant Bankers to the issue (known as Book Running Lead Managers (BRLM) in case of book built public issues), Registrars to the issue, and Bankers to the issue & Underwriters to the issue who are associated with the issue for different activities. Their addresses, telephone/fax numbers, registration number, and contact person and email addresses are disclosed in the offer documents.
i) Merchant Banker: Merchant banker does the due diligence to prepare the offer document which contains all the details about the company. They are also responsible for ensuring compliance with the legal formalities in the entire issue process and for marketing of the issue.
ii) Registrars to the Issue: They are involved in finalizing the basis of allotment in an issue and for sending refunds, allotment details, etc.
iii) Bankers to the Issue: The Bankers to the Issue enable the movement of funds in the issue process and therefore enable the registrars to finalize the basis of allotment by making clear funds status available to the Registrars.
iv) Underwriters: Underwriters are intermediaries who undertake to subscribe to the securities offered by the company in case these are not fully subscribed by the public, in case of an underwritten issue.
Please refer to page 22 of link for more information.