The activity in the primary market has picked up of late boosted by the rebound in equities in the past two months. Go Digit General Insurance, Concord Biotech, an Ahmedabad-based firm backed by RARE Enterprises, and Kolkata-based Balaji Solutions have filed their draft red herring prospectus (DRHP) with the markets regulator Securities and Exchange Board of India (SEBI), on Tuesday to launch initial public offerings.