{"id":5917,"date":"2026-09-28T15:09:53","date_gmt":"2026-09-28T08:09:53","guid":{"rendered":"https:\/\/blog.datacore.vn\/?p=5917"},"modified":"2026-09-28T15:11:25","modified_gmt":"2026-09-28T08:11:25","slug":"event-study-muc-gia-dong-cua","status":"publish","type":"post","link":"https:\/\/blog.datacore.vn\/vi\/event-study-muc-gia-dong-cua\/","title":{"rendered":"Event Study #3 | Gi\u00e1 \u0111\u00f3ng c\u1eeda ch\u01b0a ch\u1eafc l\u00e0 m\u1ee9c gi\u00e1 n\u00ean d\u00f9ng"},"content":{"rendered":"<p class=\"wp-block-paragraph\"><em>\u0110\u00e2y l\u00e0 b\u00e0i th\u1ee9 ba trong series <strong>\u201cX\u00e2y d\u1ef1ng Event Study cho th\u1ecb tr\u01b0\u1eddng ch\u1ee9ng kho\u00e1n Vi\u1ec7t Nam\u201d.<\/strong><\/em><\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><em>\u0110\u1ecdc th\u00eam:<\/em><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><em>Event Study #2 | <a href=\"https:\/\/blog.datacore.vn\/vi\/du-lieu-thi-truong-trong-ngay-2026\/\" data-type=\"link\" data-id=\"https:\/\/blog.datacore.vn\/vi\/du-lieu-thi-truong-trong-ngay-2026\/\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-custom-color\">D\u1eef li\u1ec7u th\u1ecb tr\u01b0\u1eddng trong ng\u00e0y: 7 t\u00edn hi\u1ec7u ngo\u00e0i gi\u00e1 \u0111\u00f3ng c\u1eeda<\/mark><\/a><\/em><\/li>\n\n\n\n<li><em><a href=\"https:\/\/blog.datacore.vn\/vi\/event-study-chung-khoan-viet-nam\/\" data-type=\"link\" data-id=\"https:\/\/blog.datacore.vn\/vi\/event-study-chung-khoan-viet-nam\/\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-custom-color\">Event Study #1 | X\u00e2y d\u1ef1ng nghi\u00ean c\u1ee9u s\u1ef1 ki\u1ec7n cho ch\u1ee9ng kho\u00e1n Vi\u1ec7t Nam<\/mark><\/a><\/em><\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">\u1ede b\u00e0i tr\u01b0\u1edbc, Historical Price \u0111\u00e3 \u0111\u01b0\u1ee3c nh\u00ecn d\u01b0\u1edbi m\u1ed9t g\u00f3c \u0111\u1ed9 r\u1ed9ng h\u01a1n.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">M\u1ed9t ng\u00e0y giao d\u1ecbch kh\u00f4ng ch\u1ec9 c\u00f3 gi\u00e1 m\u1edf c\u1eeda, gi\u00e1 cao nh\u1ea5t, gi\u00e1 th\u1ea5p nh\u1ea5t v\u00e0 gi\u00e1 \u0111\u00f3ng c\u1eeda. \u0110\u1eb1ng sau nh\u1eefng con s\u1ed1 \u0111\u00f3 c\u00f2n c\u00f3 kh\u1ed1i l\u01b0\u1ee3ng, gi\u00e1 tr\u1ecb giao d\u1ecbch, giao d\u1ecbch kh\u1ed1i ngo\u1ea1i, giao d\u1ecbch t\u1ef1 doanh v\u00e0 nhi\u1ec1u th\u00f4ng tin kh\u00e1c.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Nh\u01b0ng khi b\u1eaft \u0111\u1ea7u x\u00e2y d\u1ef1ng m\u1ed9t Event Study, c\u00f3 m\u1ed9t v\u1ea5n \u0111\u1ec1 t\u01b0\u1edfng nh\u01b0 r\u1ea5t \u0111\u01a1n gi\u1ea3n l\u1ea1i xu\u1ea5t hi\u1ec7n:<\/p>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<p class=\"wp-block-paragraph\"><strong>N\u1ebfu c\u1ea7n t\u00ednh l\u1ee3i su\u1ea5t c\u1ee7a m\u1ed9t c\u1ed5 phi\u1ebfu, cu\u1ed1i c\u00f9ng n\u00ean s\u1eed d\u1ee5ng m\u1ee9c gi\u00e1 n\u00e0o?<\/strong><\/p>\n<\/blockquote>\n\n\n\n<p class=\"wp-block-paragraph\">C\u00e2u h\u1ecfi n\u00e0y quan tr\u1ecdng h\u01a1n v\u1ebb ngo\u00e0i c\u1ee7a n\u00f3.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">B\u1edfi v\u00ec trong Event Study, ch\u00fang ta kh\u00f4ng tr\u1ef1c ti\u1ebfp ph\u00e2n t\u00edch m\u1ed9t chu\u1ed7i gi\u00e1.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Ch\u00fang ta ph\u00e2n t\u00edch <strong>return<\/strong>.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">V\u00e0 return l\u1ea1i \u0111\u01b0\u1ee3c t\u00ednh t\u1eeb gi\u00e1.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u0110i\u1ec1u \u0111\u00f3 c\u00f3 ngh\u0129a l\u00e0 m\u1ed9t l\u1ef1a ch\u1ecdn \u1edf ngay b\u01b0\u1edbc \u0111\u1ea7u ti\u00ean c\u00f3 th\u1ec3 \u0111i xuy\u00ean su\u1ed1t c\u1ea3 pipeline.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">M\u1ed9t v\u00ed d\u1ee5 r\u1ea5t \u0111\u01a1n gi\u1ea3n<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Gi\u1ea3 s\u1eed m\u1ed9t c\u1ed5 phi\u1ebfu \u0111ang giao d\u1ecbch \u1edf m\u1ee9c 100.000 \u0111\u1ed3ng v\u00e0o ng\u00e0y th\u1ee9 nh\u1ea5t.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Ng\u00e0y h\u00f4m sau, gi\u00e1 \u0111\u00f3ng c\u1eeda c\u00f2n 90.000 \u0111\u1ed3ng.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">N\u1ebfu ch\u1ec9 nh\u00ecn v\u00e0o hai m\u1ee9c gi\u00e1 n\u00e0y, ph\u00e9p t\u00ednh r\u1ea5t \u0111\u01a1n gi\u1ea3n:<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Return = 90.000 \/ 100.000 - 1 = -10%<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">C\u1ed5 phi\u1ebfu gi\u1ea3m 10%.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Nh\u01b0ng h\u00e3y thay \u0111\u1ed5i m\u1ed9t chi ti\u1ebft.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Gi\u1ea3 s\u1eed gi\u1eefa hai ng\u00e0y \u0111\u00f3, doanh nghi\u1ec7p th\u1ef1c hi\u1ec7n m\u1ed9t corporate action khi\u1ebfn gi\u00e1 tham chi\u1ebfu \u0111\u01b0\u1ee3c \u0111i\u1ec1u ch\u1ec9nh.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">L\u00fac n\u00e0y, vi\u1ec7c l\u1ea5y hai m\u1ee9c gi\u00e1 quan s\u00e1t \u0111\u01b0\u1ee3c v\u00e0 chia tr\u1ef1c ti\u1ebfp cho nhau c\u00f3 th\u1ec3 kh\u00f4ng c\u00f2n ph\u1ea3n \u00e1nh \u0111\u00fang m\u1ee9c sinh l\u1ee3i m\u00e0 nh\u00e0 \u0111\u1ea7u t\u01b0 th\u1ef1c s\u1ef1 tr\u1ea3i qua.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u0110\u00e2y ch\u00ednh l\u00e0 l\u00fac kh\u00e1i ni\u1ec7m <strong>adjusted price<\/strong> tr\u1edf n\u00ean quan tr\u1ecdng.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">Gi\u00e1 thay \u0111\u1ed5i kh\u00f4ng ph\u1ea3i l\u00fac n\u00e0o c\u0169ng c\u00f3 ngh\u0129a l\u00e0 gi\u00e1 tr\u1ecb thay \u0111\u1ed5i<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">H\u00e3y t\u01b0\u1edfng t\u01b0\u1ee3ng m\u1ed9t c\u1ed5 phi\u1ebfu \u0111ang c\u00f3 gi\u00e1 100.000 \u0111\u1ed3ng.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Doanh nghi\u1ec7p th\u1ef1c hi\u1ec7n chia c\u1ed5 t\u1ee9c b\u1eb1ng c\u1ed5 phi\u1ebfu theo t\u1ef7 l\u1ec7 20%.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Sau khi \u0111i\u1ec1u ch\u1ec9nh, gi\u00e1 tham chi\u1ebfu c\u00f3 th\u1ec3 gi\u1ea3m xu\u1ed1ng kho\u1ea3ng 83.333 \u0111\u1ed3ng.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">N\u1ebfu ch\u1ec9 nh\u00ecn v\u00e0o price series ch\u01b0a \u0111i\u1ec1u ch\u1ec9nh, bi\u1ec3u \u0111\u1ed3 s\u1ebd cho th\u1ea5y m\u1ed9t c\u00fa gi\u1ea3m r\u1ea5t l\u1edbn.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Nh\u01b0ng \u0111i\u1ec1u g\u00ec th\u1ef1c s\u1ef1 x\u1ea3y ra?<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Nh\u00e0 \u0111\u1ea7u t\u01b0 kh\u00f4ng \u0111\u01a1n gi\u1ea3n l\u00e0 m\u1ea5t \u0111i kho\u1ea3ng 16,7% gi\u00e1 tr\u1ecb.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">S\u1ed1 l\u01b0\u1ee3ng c\u1ed5 phi\u1ebfu m\u00e0 h\u1ecd n\u1eafm gi\u1eef c\u0169ng thay \u0111\u1ed5i.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">V\u00ec v\u1eady, m\u1ed9t ph\u1ea7n bi\u1ebfn \u0111\u1ed9ng c\u1ee7a m\u1ee9c gi\u00e1 \u0111\u1ebfn t\u1eeb <strong>corporate action<\/strong>, ch\u1ee9 kh\u00f4ng ph\u1ea3i \u0111\u01a1n thu\u1ea7n t\u1eeb vi\u1ec7c th\u1ecb tr\u01b0\u1eddng thay \u0111\u1ed5i k\u1ef3 v\u1ecdng v\u1ec1 doanh nghi\u1ec7p.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u0110\u00e2y l\u00e0 m\u1ed9t \u0111i\u1ec3m \u0111\u1eb7c bi\u1ec7t quan tr\u1ecdng \u0111\u1ed1i v\u1edbi Event Study.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">B\u1edfi m\u1ee5c ti\u00eau c\u1ee7a Event Study l\u00e0 x\u00e1c \u0111\u1ecbnh ph\u1ea3n \u1ee9ng c\u1ee7a th\u1ecb tr\u01b0\u1eddng xung quanh m\u1ed9t s\u1ef1 ki\u1ec7n. Ph\u01b0\u01a1ng ph\u00e1p n\u00e0y d\u1ef1a tr\u00ean vi\u1ec7c so s\u00e1nh return th\u1ef1c t\u1ebf v\u1edbi m\u1ed9t m\u1ee9c return k\u1ef3 v\u1ecdng \u0111\u1ec3 t\u00ednh <strong>abnormal return<\/strong>.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">N\u1ebfu chu\u1ed7i return \u0111\u1ea7u v\u00e0o \u0111\u00e3 ch\u1ee9a nh\u1eefng bi\u1ebfn \u0111\u1ed9ng gi\u00e1 kh\u00f4ng ph\u1ea3n \u00e1nh \u0111\u00fang thay \u0111\u1ed5i kinh t\u1ebf c\u1ee7a kho\u1ea3n \u0111\u1ea7u t\u01b0, k\u1ebft qu\u1ea3 ph\u00eda sau c\u0169ng c\u00f3 th\u1ec3 b\u1ecb \u1ea3nh h\u01b0\u1edfng.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">V\u1eady <code>close_price<\/code> c\u00f3 sai kh\u00f4ng?<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Kh\u00f4ng.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u0110\u00e2y l\u00e0 \u0111i\u1ec3m c\u1ea7n ph\u00e2n bi\u1ec7t r\u00f5.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong><code>close_price<\/code> kh\u00f4ng ph\u1ea3i l\u00e0 m\u1ed9t m\u1ee9c gi\u00e1 sai.<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">N\u00f3 ph\u1ea3n \u00e1nh gi\u00e1 \u0111\u00f3ng c\u1eeda \u0111\u01b0\u1ee3c quan s\u00e1t tr\u00ean th\u1ecb tr\u01b0\u1eddng trong ng\u00e0y giao d\u1ecbch.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">V\u1ea5n \u0111\u1ec1 n\u1eb1m \u1edf <strong>m\u1ee5c \u0111\u00edch s\u1eed d\u1ee5ng<\/strong>.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">N\u1ebfu c\u1ea7n bi\u1ebft:<\/p>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<p class=\"wp-block-paragraph\">\"C\u1ed5 phi\u1ebfu \u0111\u00f3ng c\u1eeda \u1edf m\u1ee9c bao nhi\u00eau v\u00e0o ng\u00e0y h\u00f4m \u0111\u00f3?\"<\/p>\n<\/blockquote>\n\n\n\n<p class=\"wp-block-paragraph\"><code>close_price<\/code> l\u00e0 th\u00f4ng tin r\u1ea5t tr\u1ef1c ti\u1ebfp.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Nh\u01b0ng n\u1ebfu c\u00e2u h\u1ecfi l\u00e0:<\/p>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<p class=\"wp-block-paragraph\">\"C\u1ed5 phi\u1ebfu \u0111\u00e3 t\u1ea1o ra m\u1ee9c sinh l\u1ee3i bao nhi\u00eau gi\u1eefa hai th\u1eddi \u0111i\u1ec3m?\"<\/p>\n<\/blockquote>\n\n\n\n<p class=\"wp-block-paragraph\">th\u00ec c\u1ea7n xem x\u00e9t li\u1ec7u chu\u1ed7i gi\u00e1 c\u00f3 c\u1ea7n \u0111\u01b0\u1ee3c \u0111i\u1ec1u ch\u1ec9nh hay kh\u00f4ng.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u0110\u00e2y l\u00e0 s\u1ef1 kh\u00e1c bi\u1ec7t gi\u1eefa <strong>observed price<\/strong> v\u00e0 <strong>research-ready price series<\/strong>.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">Nh\u00ecn v\u00e0o Historical Price c\u1ee7a DataCore<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">\u0110\u00e2y c\u0169ng l\u00e0 l\u00fd do b\u1ed9 <a href=\"https:\/\/datacore.vn\/vi\/get-data\/datasets\/dataset_historical_price\" data-type=\"link\" data-id=\"https:\/\/datacore.vn\/vi\/get-data\/datasets\/dataset_historical_price\" target=\"_blank\" rel=\"noopener\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-custom-color\">Historical Price<\/mark><\/a> kh\u00f4ng ch\u1ec9 l\u01b0u m\u1ed9t tr\u01b0\u1eddng gi\u00e1 duy nh\u1ea5t.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Trong dataset c\u00f3 c\u00e1c tr\u01b0\u1eddng nh\u01b0:<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><code>close_price<\/code><\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><code>basic_price<\/code><\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><code>adj_ratio<\/code><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Ba tr\u01b0\u1eddng n\u00e0y kh\u00f4ng ph\u1ea3i ba c\u00e1ch g\u1ecdi kh\u00e1c nhau c\u1ee7a c\u00f9ng m\u1ed9t th\u1ee9.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Ch\u00fang cung c\u1ea5p nh\u1eefng th\u00f4ng tin kh\u00e1c nhau \u0111\u1ec3 ng\u01b0\u1eddi s\u1eed d\u1ee5ng c\u00f3 th\u1ec3 hi\u1ec3u v\u00e0 x\u1eed l\u00fd chu\u1ed7i gi\u00e1 ph\u00f9 h\u1ee3p v\u1edbi m\u1ee5c \u0111\u00edch nghi\u00ean c\u1ee9u.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">V\u00e0 khi x\u00e2y d\u1ef1ng m\u1ed9t pipeline nghi\u00ean c\u1ee9u, \u0111i\u1ec1u quan tr\u1ecdng kh\u00f4ng ph\u1ea3i l\u00e0 ch\u1ecdn m\u1ed9t tr\u01b0\u1eddng v\u00ec n\u00f3 \"ph\u1ed5 bi\u1ebfn nh\u1ea5t\".<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u0110i\u1ec1u quan tr\u1ecdng l\u00e0 ph\u1ea3i hi\u1ec3u:<\/p>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<p class=\"wp-block-paragraph\"><strong>Tr\u01b0\u1eddng d\u1eef li\u1ec7u \u0111\u00f3 \u0111ang \u0111\u1ea1i di\u1ec7n cho \u0111i\u1ec1u g\u00ec?<\/strong><\/p>\n<\/blockquote>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">T\u1eeb Price \u0111\u1ebfn Return<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">\u0110\u00e2y l\u00e0 b\u01b0\u1edbc chuy\u1ec3n quan tr\u1ecdng c\u1ee7a c\u1ea3 series.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Historical Price cho ch\u00fang ta m\u1ed9t chu\u1ed7i gi\u00e1:<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>Date          Price\n\n01\/07         100\n02\/07         102\n03\/07         101\n04\/07         105<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">Nh\u01b0ng Event Study c\u1ea7n m\u1ed9t chu\u1ed7i kh\u00e1c:<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>Date          Return\n\n01\/07           -\n02\/07         2.00%\n03\/07        -0.98%\n04\/07         3.96%<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">Return bi\u1ebfn d\u1eef li\u1ec7u gi\u00e1 th\u00e0nh m\u1ed9t th\u01b0\u1edbc \u0111o c\u00f3 th\u1ec3 so s\u00e1nh gi\u1eefa c\u00e1c ng\u00e0y.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">V\u00e0 khi c\u00f3 return c\u1ee7a c\u1ed5 phi\u1ebfu, ch\u00fang ta m\u1edbi c\u00f3 th\u1ec3 \u0111\u1eb7t n\u00f3 c\u1ea1nh return c\u1ee7a th\u1ecb tr\u01b0\u1eddng.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Sau \u0111\u00f3 m\u1edbi ti\u1ebfn t\u1edbi:<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>Stock Return\n      \u2502\n      \u25bc\nMarket Return\n      \u2502\n      \u25bc\nExpected Return\n      \u2502\n      \u25bc\nAbnormal Return<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u0110\u00e2y c\u0169ng l\u00e0 l\u00fd do d\u1eef li\u1ec7u daily return \u0111\u00f3ng vai tr\u00f2 quan tr\u1ecdng trong Event Study. C\u00e1c nghi\u00ean c\u1ee9u ph\u01b0\u01a1ng ph\u00e1p kinh \u0111i\u1ec3n \u0111\u00e3 xem x\u00e9t tr\u1ef1c ti\u1ebfp \u0111\u1eb7c t\u00ednh c\u1ee7a daily stock returns v\u00e0 c\u00e1ch ch\u00fang \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng trong Event Study.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">Nh\u01b0ng v\u1eabn c\u00f2n m\u1ed9t c\u00e2u h\u1ecfi kh\u00e1c<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Ngay c\u1ea3 khi \u0111\u00e3 quy\u1ebft \u0111\u1ecbnh s\u1eed d\u1ee5ng m\u1ed9t chu\u1ed7i gi\u00e1 ph\u00f9 h\u1ee3p, v\u1eabn c\u00f2n m\u1ed9t v\u1ea5n \u0111\u1ec1:<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>T\u00ednh return nh\u01b0 th\u1ebf n\u00e0o?<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">C\u00f3 th\u1ec3 s\u1eed d\u1ee5ng simple return:<math xmlns=\"http:\/\/www.w3.org\/1998\/Math\/MathML\" display=\"block\"><semantics><mrow><msub><mi>R<\/mi><mi>t<\/mi><\/msub><mo>=<\/mo><mfrac><msub><mi>P<\/mi><mi>t<\/mi><\/msub><msub><mi>P<\/mi><mrow><mi>t<\/mi><mo>\u2212<\/mo><mn>1<\/mn><\/mrow><\/msub><\/mfrac><mo>\u2212<\/mo><mn>1<\/mn><\/mrow><annotation encoding=\"application\/x-tex\">R_t = \\frac{P_t}{P_{t-1}} - 1<\/annotation><\/semantics><\/math><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Ho\u1eb7c log return:<math xmlns=\"http:\/\/www.w3.org\/1998\/Math\/MathML\" display=\"block\"><semantics><mrow><msub><mi>r<\/mi><mi>t<\/mi><\/msub><mo>=<\/mo><mi>ln<\/mi><mo>\u2061<\/mo><mrow><mo fence=\"true\">(<\/mo><mfrac><msub><mi>P<\/mi><mi>t<\/mi><\/msub><msub><mi>P<\/mi><mrow><mi>t<\/mi><mo>\u2212<\/mo><mn>1<\/mn><\/mrow><\/msub><\/mfrac><mo fence=\"true\">)<\/mo><\/mrow><\/mrow><annotation encoding=\"application\/x-tex\">r_t = \\ln\\left(\\frac{P_t}{P_{t-1}}\\right)<\/annotation><\/semantics><\/math><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Hai c\u00e1ch t\u00ednh n\u00e0y c\u00f3 quan h\u1ec7 r\u1ea5t g\u1ea7n nhau \u0111\u1ed1i v\u1edbi nh\u1eefng bi\u1ebfn \u0111\u1ed9ng nh\u1ecf, nh\u01b0ng kh\u00f4ng ho\u00e0n to\u00e0n gi\u1ed1ng nhau.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">V\u00e0 \u0111\u00e2y s\u1ebd l\u00e0 b\u01b0\u1edbc ti\u1ebfp theo.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">B\u1edfi sau khi gi\u1ea3i quy\u1ebft c\u00e2u h\u1ecfi <strong>\"d\u00f9ng gi\u00e1 n\u00e0o?\"<\/strong>, ch\u00fang ta c\u1ea7n gi\u1ea3i quy\u1ebft c\u00e2u h\u1ecfi ti\u1ebfp theo:<\/p>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<p class=\"wp-block-paragraph\"><strong>\"T\u1eeb m\u1ee9c gi\u00e1 \u0111\u00f3, l\u00e0m th\u1ebf n\u00e0o \u0111\u1ec3 t\u1ea1o ra m\u1ed9t chu\u1ed7i return \u0111\u00e1ng tin c\u1eady cho Event Study?\"<\/strong><\/p>\n<\/blockquote>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">T\u1eeb m\u1ed9t m\u1ee9c gi\u00e1 \u0111\u1ebfn m\u1ed9t nghi\u00ean c\u1ee9u<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">\u0110\u00e2y c\u00f3 l\u1ebd l\u00e0 \u0111i\u1ec1u quan tr\u1ecdng nh\u1ea5t c\u1ea7n gi\u1eef l\u1ea1i sau b\u00e0i vi\u1ebft n\u00e0y.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Trong m\u1ed9t Event Study, <code>close_price<\/code> ch\u1ec9 l\u00e0 \u0111i\u1ec3m b\u1eaft \u0111\u1ea7u.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">M\u1ed9t m\u1ee9c gi\u00e1 quan s\u00e1t \u0111\u01b0\u1ee3c c\u1ea7n \u0111\u01b0\u1ee3c \u0111\u1eb7t trong \u0111\u00fang b\u1ed1i c\u1ea3nh c\u1ee7a n\u00f3.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Corporate actions c\u1ea7n \u0111\u01b0\u1ee3c xem x\u00e9t.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Adjustment c\u1ea7n \u0111\u01b0\u1ee3c hi\u1ec3u.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Return c\u1ea7n \u0111\u01b0\u1ee3c t\u00ednh \u0111\u00fang.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Sau \u0111\u00f3, return c\u1ee7a c\u1ed5 phi\u1ebfu m\u1edbi c\u00f3 th\u1ec3 \u0111\u01b0\u1ee3c \u0111\u01b0a v\u00e0o nh\u1eefng b\u01b0\u1edbc ti\u1ebfp theo c\u1ee7a nghi\u00ean c\u1ee9u.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">N\u00f3i c\u00e1ch kh\u00e1c:<\/p>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<p class=\"wp-block-paragraph\"><strong>Kh\u00f4ng ph\u1ea3i c\u1ee9 c\u00f3 Historical Price l\u00e0 \u0111\u00e3 c\u00f3 Return. V\u00e0 kh\u00f4ng ph\u1ea3i c\u1ee9 c\u00f3 Return l\u00e0 \u0111\u00e3 c\u00f3 m\u1ed9t Event Study t\u1ed1t.<\/strong><\/p>\n<\/blockquote>\n\n\n\n<p class=\"wp-block-paragraph\">Ch\u1ea5t l\u01b0\u1ee3ng c\u1ee7a nghi\u00ean c\u1ee9u \u0111\u01b0\u1ee3c h\u00ecnh th\u00e0nh qua t\u1eebng b\u01b0\u1edbc r\u1ea5t nh\u1ecf nh\u01b0 v\u1eady.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">B\u00e0i ti\u1ebfp theo<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Event Study #4 | T\u1eeb Historical Price \u0111\u1ebfn Daily Return: Bi\u1ebfn chuy\u1ec3n \u0111\u1ed9ng gi\u00e1 th\u00e0nh d\u1eef li\u1ec7u c\u00f3 th\u1ec3 nghi\u00ean c\u1ee9u<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">B\u00e0i ti\u1ebfp theo s\u1ebd b\u1eaft \u0111\u1ea7u t\u1eeb ch\u00ednh nh\u1eefng m\u1ee9c gi\u00e1 \u0111\u00e3 \u0111\u01b0\u1ee3c l\u1ef1a ch\u1ecdn \u1edf b\u00e0i n\u00e0y v\u00e0 x\u00e2y d\u1ef1ng Daily Return t\u1eebng b\u01b0\u1edbc.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">T\u1eeb \u0111\u00f3, ch\u00fang ta s\u1ebd c\u00f3 vi\u00ean g\u1ea1ch ti\u1ebfp theo \u0111\u1ec3 ti\u1ebfn \u0111\u1ebfn Market Return v\u00e0 cu\u1ed1i c\u00f9ng l\u00e0 Abnormal Return.<\/p>","protected":false},"excerpt":{"rendered":"<p>\u0110\u00e2y l\u00e0 b\u00e0i th\u1ee9 ba trong series \u201cX\u00e2y d\u1ef1ng Event Study cho th\u1ecb tr\u01b0\u1eddng ch\u1ee9ng kho\u00e1n Vi\u1ec7t Nam\u201d. \u0110\u1ecdc th\u00eam: \u1ede b\u00e0i tr\u01b0\u1edbc, Historical Price \u0111\u00e3 \u0111\u01b0\u1ee3c nh\u00ecn d\u01b0\u1edbi m\u1ed9t g\u00f3c \u0111\u1ed9 r\u1ed9ng h\u01a1n. M\u1ed9t ng\u00e0y giao d\u1ecbch kh\u00f4ng ch\u1ec9 c\u00f3 gi\u00e1 m\u1edf c\u1eeda, gi\u00e1 cao nh\u1ea5t, gi\u00e1 th\u1ea5p nh\u1ea5t v\u00e0 gi\u00e1 \u0111\u00f3ng c\u1eeda. \u0110\u1eb1ng [&hellip;]<\/p>\n","protected":false},"author":13,"featured_media":5914,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"content-type":"","_uag_custom_page_level_css":"","_swt_meta_header_display":false,"_swt_meta_footer_display":false,"_swt_meta_site_title_display":false,"_swt_meta_sticky_header":false,"_swt_meta_transparent_header":false,"footnotes":""},"categories":[19,1771],"tags":[],"class_list":["post-5917","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-blog-vi","category-finance-vi"],"uagb_featured_image_src":{"full":["https:\/\/blog.datacore.vn\/wp-content\/uploads\/2026\/09\/image-2.png",1529,860,false],"thumbnail":["https:\/\/blog.datacore.vn\/wp-content\/uploads\/2026\/09\/image-2-150x150.png",150,150,true],"medium":["https:\/\/blog.datacore.vn\/wp-content\/uploads\/2026\/09\/image-2-300x169.png",300,169,true],"medium_large":["https:\/\/blog.datacore.vn\/wp-content\/uploads\/2026\/09\/image-2-766x431.png",766,431,true],"large":["https:\/\/blog.datacore.vn\/wp-content\/uploads\/2026\/09\/image-2-1024x576.png",1024,576,true],"1536x1536":["https:\/\/blog.datacore.vn\/wp-content\/uploads\/2026\/09\/image-2.png",1529,860,false],"2048x2048":["https:\/\/blog.datacore.vn\/wp-content\/uploads\/2026\/09\/image-2.png",1529,860,false],"trp-custom-language-flag":["https:\/\/blog.datacore.vn\/wp-content\/uploads\/2026\/09\/image-2-18x10.png",18,10,true]},"uagb_author_info":{"display_name":"Bui Huong","author_link":"https:\/\/blog.datacore.vn\/vi\/author\/huongbui\/"},"uagb_comment_info":0,"uagb_excerpt":"\u0110\u00e2y l\u00e0 b\u00e0i th\u1ee9 ba trong series \u201cX\u00e2y d\u1ef1ng Event Study cho th\u1ecb tr\u01b0\u1eddng ch\u1ee9ng kho\u00e1n Vi\u1ec7t Nam\u201d. \u0110\u1ecdc th\u00eam: \u1ede b\u00e0i tr\u01b0\u1edbc, Historical Price \u0111\u00e3 \u0111\u01b0\u1ee3c nh\u00ecn d\u01b0\u1edbi m\u1ed9t g\u00f3c \u0111\u1ed9 r\u1ed9ng h\u01a1n. M\u1ed9t ng\u00e0y giao d\u1ecbch kh\u00f4ng ch\u1ec9 c\u00f3 gi\u00e1 m\u1edf c\u1eeda, gi\u00e1 cao nh\u1ea5t, gi\u00e1 th\u1ea5p nh\u1ea5t v\u00e0 gi\u00e1 \u0111\u00f3ng c\u1eeda. \u0110\u1eb1ng&hellip;","_links":{"self":[{"href":"https:\/\/blog.datacore.vn\/vi\/wp-json\/wp\/v2\/posts\/5917","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blog.datacore.vn\/vi\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blog.datacore.vn\/vi\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blog.datacore.vn\/vi\/wp-json\/wp\/v2\/users\/13"}],"replies":[{"embeddable":true,"href":"https:\/\/blog.datacore.vn\/vi\/wp-json\/wp\/v2\/comments?post=5917"}],"version-history":[{"count":4,"href":"https:\/\/blog.datacore.vn\/vi\/wp-json\/wp\/v2\/posts\/5917\/revisions"}],"predecessor-version":[{"id":5967,"href":"https:\/\/blog.datacore.vn\/vi\/wp-json\/wp\/v2\/posts\/5917\/revisions\/5967"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/blog.datacore.vn\/vi\/wp-json\/wp\/v2\/media\/5914"}],"wp:attachment":[{"href":"https:\/\/blog.datacore.vn\/vi\/wp-json\/wp\/v2\/media?parent=5917"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blog.datacore.vn\/vi\/wp-json\/wp\/v2\/categories?post=5917"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blog.datacore.vn\/vi\/wp-json\/wp\/v2\/tags?post=5917"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}