{"id":369046,"date":"2026-08-06T17:40:08","date_gmt":"2026-08-06T12:10:08","guid":{"rendered":"https:\/\/forumias.com\/blog\/?p=369046"},"modified":"2026-08-06T17:40:08","modified_gmt":"2026-08-06T12:10:08","slug":"closing-auction-session-cas","status":"publish","type":"post","link":"https:\/\/forumias.com\/blog\/closing-auction-session-cas\/","title":{"rendered":"Closing Auction Session (CAS)"},"content":{"rendered":"<div class=\"content-box-green\">\n<p><strong>News:<\/strong> SEBI has introduced the Closing Auction Session (CAS) for eligible F&amp;O stocks, effective from 3 August 2026, replacing the existing closing price methodology.<\/p>\n<\/div>\n<h2 class=\"red-h2-box\">About Closing Auction Session (CAS)<\/h2>\n<figure id=\"attachment_369055\" aria-describedby=\"caption-attachment-369055\" style=\"width: 624px\" class=\"wp-caption aligncenter\"><img data-recalc-dims=\"1\" loading=\"lazy\" decoding=\"async\" class=\" wp-image-369055\" src=\"https:\/\/i0.wp.com\/forumias.com\/blog\/wp-content\/uploads\/2026\/08\/Source-Trading-View.jpg?resize=624%2C356&#038;ssl=1\" alt=\"Closing Auction Session (CAS)\" width=\"624\" height=\"356\" srcset=\"https:\/\/i0.wp.com\/forumias.com\/blog\/wp-content\/uploads\/2026\/08\/Source-Trading-View.jpg?resize=300%2C171&amp;ssl=1 300w, https:\/\/i0.wp.com\/forumias.com\/blog\/wp-content\/uploads\/2026\/08\/Source-Trading-View.jpg?resize=1024%2C582&amp;ssl=1 1024w, https:\/\/i0.wp.com\/forumias.com\/blog\/wp-content\/uploads\/2026\/08\/Source-Trading-View.jpg?w=1390&amp;ssl=1 1390w\" sizes=\"auto, (max-width: 624px) 100vw, 624px\" \/><figcaption id=\"caption-attachment-369055\" class=\"wp-caption-text\">Source &#8211; Trading View<\/figcaption><\/figure>\n<ul>\n<li><strong>Closing Auction Session (CAS)<\/strong>\u00a0is an <strong>auction-based session<\/strong> to <strong>determine the official closing price<\/strong> of eligible F&amp;O stocks.<\/li>\n<li><strong>Introduced by:<\/strong> It is introduced by <strong>Securities and Exchange Board of India (SEBI).<\/strong><\/li>\n<li><strong>Implemented by: <\/strong>The <strong>National Stock Exchange (NSE) and BSE <\/strong>are implementing CAS simultaneously.<\/li>\n<li><strong>Effective from:<\/strong> It is effective from <strong>3 August 2026.<\/strong><\/li>\n<li><strong>Aim: <\/strong>It\u2019s aims is to <strong>improve price discovery, transparency, execution of large orders<\/strong>, and ensure that the <strong>closing price better reflects overall market demand and supply.<\/strong><\/li>\n<li><strong>Working Mechanism:<\/strong>\n<ul>\n<li><strong>Start of the Auction Session:<\/strong> The <strong>Closing Auction Session (CAS) begins at 3:15 P.M.<\/strong> for eligible stocks in the Futures and Options (F&amp;O) segment.\n<ul>\n<li>At the start of the session, the <strong>system calculates a reference price based on the Volume Weighted Average Price (VWAP) of trades executed during the last 30 minutes<\/strong> of the Continuous Trading Session (CTS).<\/li>\n<li><strong>This reference price serves as the starting point for the auction.<\/strong><\/li>\n<\/ul>\n<\/li>\n<li><strong>Order Collection:<\/strong> During the auction window, <strong>eligible buy and sell orders are collected instead of being executed immediately.<\/strong>\n<ul>\n<li>The order entry <strong>window closes at a randomly selected time between 3:28 P.M. and 3:30 P.M.<\/strong> to discourage last-second order placement and support a fair price discovery process.<\/li>\n<\/ul>\n<\/li>\n<li><strong>Price Discovery:<\/strong> Then, the stock exchange determines a single <strong>equilibrium price,<\/strong> which is the <strong>price at which the maximum number of shares can be traded.<\/strong>\n<ul>\n<li>This <strong>price better reflects the overall market demand and supply.<\/strong><\/li>\n<\/ul>\n<\/li>\n<li><strong>Trade Execution and Closing Price:<\/strong> <strong>All eligible trades are executed at the equilibrium price.<\/strong>\n<ul>\n<li>This <strong>equilibrium price becomes the official closing price of the stock for that trading day.<\/strong><\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<\/li>\n<li><strong>Key Features:<\/strong>\n<ul>\n<li><strong>Auction-based Price Discovery:<\/strong> The <strong>official closing price<\/strong> is determined through a <strong>single equilibrium price.<\/strong><\/li>\n<li><strong>Initial Coverage:<\/strong> CAS <strong>initially applies only to stocks with available F&amp;O<\/strong> contracts.<\/li>\n<li><strong>Existing Method for Others:<\/strong> Securities not covered under CAS will continue with the existing VWAP-based closing price methodology.<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<h2 class=\"yellow-h2-box\">About Continuous Trading Session (CTS)<\/h2>\n<ul>\n<li><strong>Order Execution:<\/strong>\n<ul>\n<li>In the <strong>Continuous Trading Session (CTS)<\/strong>, buy and sell orders are matched and <strong>executed immediately whenever prices match. <\/strong><\/li>\n<li>In contrast, the <strong>Closing Auction Session (CAS) first collects all eligible orders and executes them together at a single equilibrium price.<\/strong><\/li>\n<\/ul>\n<\/li>\n<li><strong>Closing Price:<\/strong>\n<ul>\n<li><strong>Earlier<\/strong>, the <strong>official closing price<\/strong> was determined using the Volume Weighted Average Price (VWAP) of<strong> trades executed during the last 30 minutes of CTS. <\/strong><\/li>\n<li><strong>Under CAS<\/strong>, the closing <strong>price is determined through an auction-based mechanism.\u00a0<\/strong><\/li>\n<li><strong>Applicability:<\/strong> Securities <strong>not covered under CAS will continue to trade under the existing CTS<\/strong>.<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"<p>News: SEBI has introduced the Closing Auction Session (CAS) for eligible F&amp;O stocks, effective from 3 August 2026, replacing the existing closing price methodology. About Closing Auction Session (CAS) Closing Auction Session (CAS)\u00a0is an auction-based session to determine the official closing price of eligible F&amp;O stocks. Introduced by: It is introduced by Securities and Exchange&hellip; <a class=\"more-link\" href=\"https:\/\/forumias.com\/blog\/closing-auction-session-cas\/\">Continue reading <span class=\"screen-reader-text\">Closing Auction Session (CAS)<\/span><\/a><\/p>\n","protected":false},"author":10401,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"footnotes":""},"categories":[1566,3127,12039],"tags":[11872],"class_list":["post-369046","post","type-post","status-publish","format-standard","hentry","category-daily-factly-articles","category-economy","category-knolls","tag-9pm-daily-factly","entry"],"jetpack_featured_media_url":"","views":"","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/forumias.com\/blog\/wp-json\/wp\/v2\/posts\/369046","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/forumias.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/forumias.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/forumias.com\/blog\/wp-json\/wp\/v2\/users\/10401"}],"replies":[{"embeddable":true,"href":"https:\/\/forumias.com\/blog\/wp-json\/wp\/v2\/comments?post=369046"}],"version-history":[{"count":0,"href":"https:\/\/forumias.com\/blog\/wp-json\/wp\/v2\/posts\/369046\/revisions"}],"wp:attachment":[{"href":"https:\/\/forumias.com\/blog\/wp-json\/wp\/v2\/media?parent=369046"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/forumias.com\/blog\/wp-json\/wp\/v2\/categories?post=369046"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/forumias.com\/blog\/wp-json\/wp\/v2\/tags?post=369046"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}