Disclosure of shareholding requirement: exchanges and clearing corporations must report quarterly shareholding patterns to the regulator promptly. Regulation 21 requires recognised stock exchanges and recognised clearing corporations to disclose to the Board, in the Board's prescribed format, their shareholding pattern quarterly within fifteen days of quarter end, identifying the ten largest shareholders with numbers and percentage holdings and listing shareholders under regulations 17 and 18 who acquired shares in that quarter; they must also monitor and ensure ongoing compliance with the chapter's disclosure requirements.