Cognizant has said it aims to be back among India's top four IT services companies by 2027 by improving revenue, market share, bagging large deals, and gradual margin expansion.The Nasdaq-listed company does a major part of its business in India, but has trailed peers such as Tata Consultancy Services and Accenture over the last few years as growth tapered, margins squeezed, and attrition soared.