Logistics start-up Shadowfax has submitted a draft red herring prospectus to the Securities and Exchange Board of India under the regulator’s confidential filing route, according to people familiar with the matter. The Bengaluru-based company is preparing a share sale of about Rs 2,500 crore (roughly $300 million). The offering is expected to comprise a combination of new shares and secondary stock sold by existing investors and could value Shadowfax near Rs 8,500 crore. Confidential filings allow companies to gauge investor appetite and fine-tune disclosures before making the prospectus public. Shadowfax, backed by Flipkart, operates a last-mile delivery network used by e-commerce, grocery and food-delivery platforms and competes with Delhivery and Ekart.