Maize-based speciality products maker Paramesu Biotech has filed preliminary papers with the capital markets regulator SEBI to raise Rs 600 crore via an initial public offering. The IPO is a combination of fresh issuance of equity shares worth Rs 520 crore, and an offer-for-sale of Rs 80 crore by promoter Unimark Business Solutions. The promoter holds 92.19 percent shareholding in the company.