Pune-based GK Energy has filed its red herring prospectus for an IPO opening on September 19, with subscriptions open until September 23. The offering includes a fresh issue of Rs 400 crore and an offer for sale of Rs 64 crore. The company, a solar EPC player, reported revenues of Rs 1,095 crore in FY25 and has an order book of over Rs 1,000 crore.