{"id":12233,"date":"2026-05-22T13:39:13","date_gmt":"2026-05-22T13:39:13","guid":{"rendered":"https:\/\/lemonn.co.in\/blog\/glossary\/pre-open-session\/"},"modified":"2026-05-22T13:39:13","modified_gmt":"2026-05-22T13:39:13","slug":"pre-open-session","status":"publish","type":"glossary","link":"https:\/\/lemonn.co.in\/blog\/glossary\/pre-open-session\/","title":{"rendered":"Pre-Open Session"},"content":{"rendered":"<p>The Indian stock market does not start <a class=\"glossaryLink\" href=\"https:\/\/lemonn.co.in\/blog\/glossary\/trading\/\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]' tabindex=\"0\" role=\"link\">trading<\/a> at the opening bell on a clean slate. Between 9:00 a.m. and 9:15 a.m. every working day, <a class=\"glossaryLink\"  href=\"https:\/\/lemonn.co.in\/blog\/glossary\/nse\/\"  data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]'  tabindex='0' role='link'>NSE<\/a> and <a class=\"glossaryLink\"  href=\"https:\/\/lemonn.co.in\/blog\/glossary\/bse\/\"  data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]'  tabindex='0' role='link'>BSE<\/a> run a special call auction called the <a class=\"glossaryLink\" href=\"https:\/\/lemonn.co.in\/blog\/glossary\/pre-open-session\/\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]' tabindex=\"0\" role=\"link\">pre-open session<\/a>. Its job is to absorb overnight news, match buyers and sellers, and arrive at a fair opening price for each stock so that the regular session starts in an orderly way.<\/p>\n<div><strong>Key takeaways:<\/strong>\n<ul>\n<li>Pre-open session runs from 9:00 a.m. to 9:15 a.m., split into three windows: order entry, matching, and buffer.<\/li>\n<li>It establishes a single equilibrium opening price for each stock through a call auction.<\/li>\n<li>Only <a class=\"glossaryLink\" href=\"https:\/\/lemonn.co.in\/blog\/glossary\/limit-order\/\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]' tabindex=\"0\" role=\"link\">limit order<\/a>s are accepted in the order-entry window; you can modify or cancel them.<\/li>\n<li>Trades happen only at the discovered equilibrium price, not on a continuous basis.<\/li>\n<li>The pre-open mechanism helps prevent abrupt gap moves and panic in the first minute of trading.<\/li>\n<\/ul>\n<\/div>\n<h2 id=\"the-three-windows-of-pre-open\">The three windows of pre-open<\/h2>\n<p>The 15-minute session is divided as follows:<\/p>\n<ul>\n<li><strong>9:00&#x2013;9:08 a.m.<\/strong> &#x2014; Order entry, modification and cancellation. Limit orders only; <a class=\"glossaryLink\" href=\"https:\/\/lemonn.co.in\/blog\/glossary\/market-order\/\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]' tabindex=\"0\" role=\"link\">market order<\/a>s not allowed in this window for retail orders. The order book builds quietly.<\/li>\n<li><strong>9:08&#x2013;9:12 a.m.<\/strong> &#x2014; Order matching and confirmation. No new orders are accepted; the system calculates the equilibrium price.<\/li>\n<li><strong>9:12&#x2013;9:15 a.m.<\/strong> &#x2014; Buffer period. Trades from pre-open are confirmed and the system prepares for the regular session.<\/li>\n<\/ul>\n<h2 id=\"how-the-equilibrium-price-is-determined\">How the equilibrium price is determined<\/h2>\n<p>The exchange runs a &#x201C;call auction&#x201D; algorithm. It looks at all the limit orders entered in the first eight minutes and finds the single price at which the maximum number of <a class=\"glossaryLink\" href=\"https:\/\/lemonn.co.in\/blog\/glossary\/shares\/\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]' tabindex=\"0\" role=\"link\">shares<\/a> can trade. This is the equilibrium price &#x2014; the opening price for the stock when regular trading begins at 9:15 a.m.<\/p>\n<p>If multiple price levels would clear the same maximum <a class=\"glossaryLink\" href=\"https:\/\/lemonn.co.in\/blog\/glossary\/volume\/\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]' tabindex=\"0\" role=\"link\">volume<\/a>, the algorithm picks the price closest to the previous day&#x2019;s close to ensure continuity.<\/p>\n<h2 id=\"why-pre-open-exists\">Why pre-open exists<\/h2>\n<p>Without pre-open, the first few seconds of trading would be chaotic. Overnight news &#x2014; earnings, central bank decisions, global market action &#x2014; would crash into the order book all at once, creating large price spikes and unfair fills for retail orders. The pre-open absorbs this pent-up demand in a controlled auction so that the regular session opens with a meaningful, fair starting price.<\/p>\n<h2 id=\"what-you-can-and-cannot-do-in-pre-open\">What you can and cannot do in pre-open<\/h2>\n<ul>\n<li>You <em>can<\/em> place limit orders for cash <a class=\"glossaryLink\" href=\"https:\/\/lemonn.co.in\/blog\/glossary\/equity\/\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]' tabindex=\"0\" role=\"link\">equity<\/a> in the order-entry window.<\/li>\n<li>You <em>can<\/em> modify or cancel any time during the entry window.<\/li>\n<li>You <em>cannot<\/em> place market orders for retail accounts.<\/li>\n<li>F&amp;O, currency and <a class=\"glossaryLink\" href=\"https:\/\/lemonn.co.in\/blog\/glossary\/commodity\/\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]' tabindex=\"0\" role=\"link\">commodity<\/a> segments operate continuously without a pre-open call.<\/li>\n<li>Orders not matched in pre-open are migrated automatically to the regular session.<\/li>\n<\/ul>\n<h2 id=\"after-market-orders-and-pre-open\">After Market Orders and pre-open<\/h2>\n<p>AMOs placed overnight enter the pre-open queue once the <a class=\"glossaryLink\" href=\"https:\/\/lemonn.co.in\/blog\/glossary\/broker\/\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]' tabindex=\"0\" role=\"link\">broker<\/a> forwards them to the exchange &#x2014; usually a few minutes before 9:00 a.m. They are treated as fresh limit orders and participate in the auction. This means an aggressive AMO can move the opening price more than a normal day-time order.<\/p>\n<h2 id=\"practical-tips\">Practical tips<\/h2>\n<ol>\n<li>If you expect a gap opening, place limit orders inside the pre-open window &#x2014; you get a chance to participate at the discovered price.<\/li>\n<li>Be careful with very aggressive limit prices; you might end up the only person at that level and skew the auction.<\/li>\n<li>Watch the indicative quote line on your broker app between 9:00 and 9:08 &#x2014; it gives a real-time sense of where the open is heading.<\/li>\n<li>Avoid market orders fired at 9:15:00 &#x2014; <a class=\"glossaryLink\" href=\"https:\/\/lemonn.co.in\/blog\/glossary\/liquidity\/\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]' tabindex=\"0\" role=\"link\">liquidity<\/a> is thinnest at this instant.<\/li>\n<\/ol>\n<h2 id=\"frequently-asked-questions\">Frequently asked questions<\/h2>\n<div>\n<h3 id=\"do-all-listed-stocks-participate-in-pre-open\">Do all listed <a class=\"glossaryLink\" href=\"https:\/\/lemonn.co.in\/blog\/glossary\/stocks\/\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]' tabindex=\"0\" role=\"link\">stocks<\/a> participate in pre-open?<\/h3>\n<p>All <a class=\"glossaryLink\" href=\"https:\/\/lemonn.co.in\/blog\/glossary\/nifty\/\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]' tabindex=\"0\" role=\"link\">Nifty<\/a> 50 and <a class=\"glossaryLink\" href=\"https:\/\/lemonn.co.in\/blog\/glossary\/sensex\/\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]' tabindex=\"0\" role=\"link\">Sensex<\/a> stocks participate, plus newly listed scrips for their first trading day. Other stocks use the regular session from 9:15 a.m.<\/p>\n<h3 id=\"can-i-place-amos-that-participate-in-pre-open\">Can I place AMOs that participate in pre-open?<\/h3>\n<p>Yes, AMOs queued overnight are forwarded just before pre-open and enter the auction as limit orders.<\/p>\n<h3 id=\"is-pre-open-available-on-weekends\">Is pre-open available on weekends?<\/h3>\n<p>No. There is no trading on Saturdays and Sundays, so no pre-open either.<\/p>\n<h3 id=\"are-pre-open-trades-reflected-in-volume-charts\">Are pre-open trades reflected in volume charts?<\/h3>\n<p>Yes, trades that match at 9:08 a.m. show up as the day&#x2019;s opening volume bar on most charting platforms.<\/p>\n<\/div>\n","protected":false},"excerpt":{"rendered":"<p>The Indian stock market does not start trading at the opening bell on a clean slate. Between 9:00 a.m. and 9:15 a.m. every working day, NSE and BSE run a special call auction called the pre-open session. Its job is to absorb overnight news, match buyers and sellers, and arrive at a fair opening price [&#x2026;]<\/p>\n","protected":false},"author":3,"featured_media":0,"menu_order":0,"template":"","meta":{"_uag_custom_page_level_css":"","footnotes":""},"class_list":["post-12233","glossary","type-glossary","status-publish","hentry"],"blocksy_meta":[],"uagb_featured_image_src":{"full":false,"thumbnail":false,"medium":false,"medium_large":false,"large":false,"1536x1536":false,"2048x2048":false,"web-stories-poster-portrait":false,"web-stories-publisher-logo":false,"web-stories-thumbnail":false},"uagb_author_info":{"display_name":"Team Lemonn","author_link":"https:\/\/lemonn.co.in\/blog\/author\/ashu\/"},"uagb_comment_info":0,"uagb_excerpt":"The Indian stock market does not start trading at the opening bell on a clean slate. Between 9:00 a.m. and 9:15 a.m. every working day, NSE and BSE run a special call auction called the pre-open session. Its job is to absorb overnight news, match buyers and sellers, and arrive at a fair opening price&hellip;","_links":{"self":[{"href":"https:\/\/lemonn.co.in\/blog\/wp-json\/wp\/v2\/glossary\/12233","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/lemonn.co.in\/blog\/wp-json\/wp\/v2\/glossary"}],"about":[{"href":"https:\/\/lemonn.co.in\/blog\/wp-json\/wp\/v2\/types\/glossary"}],"author":[{"embeddable":true,"href":"https:\/\/lemonn.co.in\/blog\/wp-json\/wp\/v2\/users\/3"}],"version-history":[{"count":0,"href":"https:\/\/lemonn.co.in\/blog\/wp-json\/wp\/v2\/glossary\/12233\/revisions"}],"wp:attachment":[{"href":"https:\/\/lemonn.co.in\/blog\/wp-json\/wp\/v2\/media?parent=12233"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}