Four companies, including pharmaceutical formulation firm Rubicon Research and TPG Capital-backed Sai Life Sciences, have received Sebi's go-ahead to raise at least Rs 3,000 crore collectively through Initial Public Offerings (IPOs), an update with the markets regulator showed on Wednesday. The other two firms that obtained the regulator's clearance are yarn manufacturer Sanathan Textiles and auto components maker Metalman Auto. Meanwhile, BMW Ventures, which filed its preliminary IPO papers in September, withdrew the documents on October 28. The four companies -- Rubicon Research, Sai Life Sciences, Sanathan Textiles and Metalman Auto -- which filed their draft IPO papers with Sebi during July and August, obtained the regulator's observations on October 31, the update showed. In Sebi's parlance, obtaining observations means its go-ahead to float public issues. The Rs 1,085-crore IPO of Rubicon Research is a combination of a fresh issue of equity shares worth Rs 500 crore and an O