Merchant bankers play an important role in capital market issues like initial public offerings and rights issues of up to 50 lakhs. They are engaged in activities like issue management, underwriting, and providing advisory services related to projects and corporate restructuring. SEBI guidelines outline the responsibilities of merchant bankers before an issue in tasks like submitting documents and appointment of intermediaries, and after an issue in monitoring investor grievances and ensuring full subscription. The roles of merchant bankers have grown with the expansion of the new issues market, entry of foreign investors, and innovations in financial products in India.