Dematerialisation requirement enables shifting from trade-for-trade to rolling settlement when non-promoter holdings are substantially dematerialised. SEBI directs stock exchanges to consider shifting securities with connectivity to both depositories from Trade for Trade Settlement to Rolling Settlement only if at least 50% of holdings other than promoters are dematerialised, evidenced by a certificate from the RTA or, where no RTA exists, from a practicing company secretary or chartered accountant, and provided no other reasons justify continuation of TFTS; exchanges must report actions taken to SEBI in their Monthly/Quarterly Development Reports.