{"id":138212,"date":"2026-03-18T12:25:21","date_gmt":"2026-03-18T16:25:21","guid":{"rendered":"https:\/\/professional.content.cirrus.bloomberg.com\/professional2023\/insights\/markets\/is-rising-equity-market-concentration-approaching-a-turning-point\/"},"modified":"2026-03-18T12:25:42","modified_gmt":"2026-03-18T16:25:42","slug":"is-rising-equity-market-concentration-approaching-a-turning-point","status":"publish","type":[3762],"link":"https:\/\/professional.content.cirrus.bloomberg.com\/professional2023\/insights\/markets\/is-rising-equity-market-concentration-approaching-a-turning-point\/","title":{"rendered":"Is rising equity market concentration approaching a turning point?"},"content":{"rendered":"<div  class=\"bbg-row-container\">\n    <section class=\"bbg-row  text--black row-padding--top-compact row-padding--bottom-none bbg-row--full-bg-bleed\" data-anchor='row-69f27b925a7c6'>\n        \n        \n        <div\n            class=\"bbg-row--content\"\n                    >\n            \n            <p><div\n    class=\"bbg-column bbg-column--width-7\"\n    style=\"\"\n    >\n    <p><div\n    class=\"bbg-spacer bbg-spacer--lg\"\n    >\n<\/div><div\n\tclass=\"bb-wysiwyg\"\n\t\t>\n\t<p class=\"small\"><strong><span style=\"font-size: 14px; letter-spacing: 1px; color: #0062dd;\">ARTICLE<\/span><\/strong><\/p>\n\n<\/div>\n<div\n    class=\"bbg-spacer bbg-spacer--sm\"\n    >\n<\/div>    <h1 class=\"bbg-metadata bbg-metadata--title\">Is rising equity market concentration approaching a turning point?<\/h1>\n<div\n    class=\"bbg-spacer\"\n        style=\"height: 50px !important\"\n    >\n<\/div>    <ul class=\"bbg-categories_list\">\n                    <li>\n                <a href=\"https:\/\/professional.content.cirrus.bloomberg.com\/professional2023\/insights\/category\/markets\/\" rel=\"category tag\">\n                    Markets\n                <\/a>\n            <\/li>\n                    <li>\n                <a href=\"https:\/\/professional.content.cirrus.bloomberg.com\/professional2023\/insights\/category\/trading\/\" rel=\"category tag\">\n                    Trading\n                <\/a>\n            <\/li>\n            <\/ul>\n<\/p>\n\n<\/div><div\n    class=\"bbg-column bbg-column--width-5\"\n    style=\"\"\n    >\n    <div id=\"\" class=\"wpb_content_element bbg-single-image align-left\">\n    <figure class=\"bbg-single-image__figure\" style=\"max-width:100%\">\n                <img loading=\"lazy\" decoding=\"async\" width=\"1200\" height=\"800\" src=\"https:\/\/assets.bbhub.io\/image\/v1\/resize?width=auto&amp;type=webp&amp;url=https:\/\/assets.bbhub.io\/professional\/sites\/41\/364368471resiz.jpg\" class=\"bbg-single-image__image attachment-full\" alt=\"Stock market curve\" title=\"Stock market curve\" \/>\n        \n            <\/figure>\n<\/div>\n\n\n\n<\/div>\n\n\n                    <\/div>\n    <\/section>\n<\/div>\n\n<div  class=\"bbg-row-container\">\n    <section class=\"bbg-row  text--black row-padding--top-none row-padding--bottom-none bbg-row--full-bg-bleed\" data-anchor='row-69f27b927edad'>\n        \n        \n        <div\n            class=\"bbg-row--content\"\n                    >\n            \n            <p><div\n    class=\"bbg-column bbg-column--width-2\"\n    style=\"\"\n    >\n    \n<\/div><div\n    class=\"bbg-column bbg-column--width-6 bbg-column--m-width-6\"\n    style=\"\"\n    >\n    <p>    <p class=\"bbg-metadata bbg-metadata--date\">March 18, 2026<\/p>\n<div\n\tclass=\"bb-wysiwyg\"\n\t\t>\n\t<p><strong>Bloomberg Professional Services<\/strong><\/p>\n\n<\/div>\n\n<\/div><div\n    class=\"bbg-column bbg-column--width-2 bbg-column--valign-middle bbg-column--m-width-2 bbg-column--s-padding-right-2\"\n    style=\"\"\n    >\n    <div class=\"bb-tts\"\n\tdata-selector=\"main\"\n\tdata-label=\"Speak this page\"\n\tdata-custom-play=\"Play\"\n\tdata-custom-pause=\"Pause\"\n\tdata-custom-stop=\"Stop\"\n\tdata-overlay=\"false\"\n\tdata-invert=\"false\"\n\tdata-no-time=\"false\"\n\tdata-no-button-text=\"false\"\n\tdata-one-button=\"true\"\n\tdata-one-style=\"true\"\n\tdata-hide-stop=\"true\"\n\tdata-voice=\"Gordon\"\n\tdata-pitch=\"1\"\n\tdata-speed=\"1\"\n\tdata-align=\"flex-start\"\n>\n<\/div>\n\n\n<\/div><div\n    class=\"bbg-column bbg-column--width-2\"\n    style=\"\"\n    >\n    \n<\/div>\n\n\n                    <\/div>\n    <\/section>\n<\/div>\n\n<div  class=\"bbg-row-container\">\n    <section class=\"bbg-row  text--black row-padding--top-none row-padding--bottom-compact bbg-row--full-bg-bleed\" data-anchor='row-69f27b9281de2'>\n        \n        \n        <div\n            class=\"bbg-row--content\"\n                    >\n            \n            <p><div\n    class=\"bbg-column bbg-column--width-2\"\n    style=\"\"\n    >\n    \n<\/div><div\n    class=\"bbg-column bbg-column--width-8 bbg-column--has-bg-color\"\n    style=\"background-color:#e6f3ff;border-radius: 16px 16px 16px 16px;\"\n    >\n    <div class=\"wpb_content_element bbg-card  bbg-card-custom bbg-card-text-black\" id=\"card_1\" data-card_type=\"no_image\">\n      <style>#card_1 .bbg-card__innerwrapper {background-color: #e6f3ff;}#card_1 .bbg-card__innerwrapper {\n\tborder: 1px solid #e6f3ff !important;\n\t}#card_1:hover .bbg-card__innerwrapper {\n\tborder: 1px solid #e6f3ff !important;\n\t}#card_1 .bbg-card__innerwrapper {\n\tpadding: calc(var(--brand-large-padding, 40px) - 1px) !important;\n\t}#card_1 .bbg-card__innerwrapper .bbg-card__title {\n\tcolor: #000000 !important;\n\t}#card_1 .bbg-card__innerwrapper .bbg-card__content,#card_1 .bbg-card__innerwrapper .bbg-card__content p  {\n\tcolor: #000000 !important;\n\t}#card_1.bbg-card_hasImage .bbg-card__innerwrapper{padding-top: calc(var(--brand-default-padding, 16px) - 1px);padding-left: calc(var(--brand-default-padding, 16px) - 1px);padding-right: calc(var(--brand-default-padding, 16px) - 1px);}<\/style>\n  \n  \n  <div class=\"bbg-card__innerwrapper\">\n    <div class=\"bbg-card__content\">\n      \n              <div class=\"bbg-card__eyebrow\" style=\"color: #000000\">KEY TAKEAWAYS<\/div>\n      \n      \n              <div class=\"bbg-card__wysiwyg bb-wysiwyg\"><\/p>\n<ul>\n<li>U.S. equity market concentration has increased sharply over the past decade as mega-cap companies have grown faster than the broader large cap universe.<\/li>\n<li>Measures such as the effective number of stocks and sectors show that market breadth has narrowed significantly despite thousands of listed constituents.<\/li>\n<li>Recent sector rotations and reassessment of AI-related valuations raise the question of whether current concentration levels could begin to normalize.<\/li>\n<\/ul>\n<p>\n<\/div>\n          <\/div>\n\n      <\/div>\n\n  <\/div>\n\n\n<\/div><div\n    class=\"bbg-column bbg-column--width-2\"\n    style=\"\"\n    >\n    \n<\/div>\n\n\n                    <\/div>\n    <\/section>\n<\/div>\n\n<div  class=\"bbg-row-container\">\n    <section class=\"bbg-row  text--black row-padding--top-compact row-padding--bottom-compact bbg-row--full-bg-bleed\" data-anchor='row-69f27b9285246'>\n        \n        \n        <div\n            class=\"bbg-row--content\"\n                    >\n            \n            <p><div\n    class=\"bbg-column bbg-column--width-2\"\n    style=\"\"\n    >\n    \n<\/div><div\n    class=\"bbg-column bbg-column--width-8\"\n    style=\"\"\n    >\n    <div\n\tclass=\"bb-wysiwyg\"\n\t\t>\n\t<p><em>This article was written by Yingjin Gan, Head of Index Research, Antonios Lazanas, Head of Quantitative Investment Research, and Rui Dong, Quant Researcher at Bloomberg.<\/em><\/p>\n<p>Recent years have witnessed a rapid increase in equity market concentration, particularly in the U.S. The sustained rise of mega-cap companies has reshaped index structures in a way that is historically significant.<\/p>\n\n<\/div>\n\n\n<\/div>\n\n\n                    <\/div>\n    <\/section>\n<\/div>\n\n<div  class=\"bbg-row-container\">\n    <section class=\"bbg-row  text--black row-padding--top-none row-padding--bottom-none bbg-row--full-bg-bleed\" data-anchor='row-69f27b9287035'>\n        \n        \n        <div\n            class=\"bbg-row--content\"\n                    >\n            \n            <p><div\n    class=\"bbg-column bbg-column--width-3\"\n    style=\"\"\n    >\n    <p><div\n    class=\"bbg-spacer bbg-spacer--sm\"\n    >\n<\/div><hr class=\"bbg-separator bbg-separator-1\" style=\"height:1px;\" \/>\n<div\n    class=\"bbg-spacer\"\n        style=\"height: 32px !important\"\n    >\n<\/div><div\n\tclass=\"bb-wysiwyg\"\n\t\t>\n\t<p class=\"small\"><strong><span style=\"font-size: 14px; letter-spacing: 1px;\">PRODUCT MENTIONS<\/span><\/strong><\/p>\n\n<\/div>\n\n<div\n  id=\"cta_1496369321665270635\"\n  class=\"wpb_content_element bbg-cta no-icon\">\n  <style>\n    \n    \n    \n  <\/style>\n  <div\n    class=\"bbg-cta-link link-holder\"\n    data-links-type=\"cta-links\">\n    <p class=\"bbg-cta-p left\">\n      <a\n        class=\"bbg-cta-link link\"\n        href=\"https:\/\/www.bloomberg.com\/professional\/products\/indices\/\"\n        target=\"\"\n        rel=\"\"\n        data-section-name=\"Bloomberg Indices\"\n        >\n                      Bloomberg Indices\n                <\/a>\n    <\/p>\n  <\/div>\n<\/div>\n<div\n    class=\"bbg-spacer bbg-spacer--sm\"\n    >\n<\/div><div\n    class=\"bbg-spacer\"\n        style=\"height: 32px !important\"\n    >\n<\/div><hr class=\"bbg-separator bbg-separator-1\" style=\"height:1px;\" \/>\n<\/p>\n\n<\/div><div\n    class=\"bbg-column bbg-column--width-1\"\n    style=\"\"\n    >\n    \n<\/div><div\n    class=\"bbg-column bbg-column--width-6\"\n    style=\"\"\n    >\n    <div\n\tclass=\"bb-wysiwyg\"\n\t\t>\n\t<p>This shift can be illustrated by examining the <a href=\"https:\/\/www.bloomberg.com\/professional\/products\/indices\/quote\/B500:IND\">Bloomberg B500 Index<\/a>. At year-end 2015, the top five constituents had a combined market capitalization of approximately $1.9 trillion. By the end of 2025, that figure had risen to $15.9 trillion\u2014a cumulative increase of 746%. Over the same period, the total market capitalization of the index increased from $17.8 trillion to $58.4 trillion, a cumulative increase of 229%. In other words, the largest companies have grown at a rate dramatically exceeding that of the broader large cap market.<\/p>\n\n<\/div>\n\n\n<\/div><div\n    class=\"bbg-column bbg-column--width-2\"\n    style=\"\"\n    >\n    \n<\/div>\n\n\n                    <\/div>\n    <\/section>\n<\/div>\n\n<div  class=\"bbg-row-container\">\n    <section class=\"bbg-row  text--black row-padding--top-compact row-padding--bottom-none bbg-row--full-bg-bleed\" data-anchor='row-69f27b9299e66'>\n        \n        \n        <div\n            class=\"bbg-row--content\"\n                    >\n            \n            <p><div\n    class=\"bbg-column bbg-column--width-2\"\n    style=\"\"\n    >\n    \n<\/div><div\n    class=\"bbg-column bbg-column--width-8\"\n    style=\"\"\n    >\n    <div id=\"\" class=\"wpb_content_element bbg-single-image align-center\">\n    <figure class=\"bbg-single-image__figure\" style=\"max-width:100%\">\n                <img loading=\"lazy\" decoding=\"async\" width=\"979\" height=\"492\" src=\"https:\/\/assets.bbhub.io\/image\/v1\/resize?width=auto&amp;type=webp&amp;url=https:\/\/assets.bbhub.io\/professional\/sites\/41\/Exhibit-1.png\" class=\"bbg-single-image__image attachment-full\" alt=\"Bloomberg B500 Top 5 Stocks Between 2015 and 2025\" title=\"Bloomberg B500 Top 5 Stocks Between 2015 and 2025\" srcset=\"https:\/\/assets.bbhub.io\/image\/v1\/resize?width=auto&amp;type=webp&amp;url=https:\/\/assets.bbhub.io\/professional\/sites\/41\/Exhibit-1.png 979w, https:\/\/assets.bbhub.io\/image\/v1\/resize?width=auto&amp;type=webp&amp;url=https:\/\/assets.bbhub.io\/professional\/sites\/41\/Exhibit-1-552x277.png 552w, https:\/\/assets.bbhub.io\/image\/v1\/resize?width=auto&amp;type=webp&amp;url=https:\/\/assets.bbhub.io\/professional\/sites\/41\/Exhibit-1-800x402.png 800w, https:\/\/assets.bbhub.io\/image\/v1\/resize?width=auto&amp;type=webp&amp;url=https:\/\/assets.bbhub.io\/professional\/sites\/41\/Exhibit-1-768x386.png 768w, https:\/\/assets.bbhub.io\/image\/v1\/resize?width=auto&amp;type=webp&amp;url=https:\/\/assets.bbhub.io\/professional\/sites\/41\/Exhibit-1-192x96.png 192w\" sizes=\"auto, (max-width: 979px) 100vw, 979px\" \/>\n        \n            <\/figure>\n<\/div>\n\n<div\n\tclass=\"bb-wysiwyg\"\n\t\t>\n\t<h2>How has equity market concentration increased over the past decade?<\/h2>\n<p>Sector concentration has followed a similar trajectory. As shown in Exhibit 1, the top three sectors were relatively balanced, each with a market capitalization between $2.5 and $2.8 trillion in 2015. Today, the largest sector, Technology at $19.7 trillion &#8211; is more than double the second and third largest sector (Financials at $7.8 trillion and Communications at $7.03 trillion). The dispersion across sectors is now materially wider than a decade ago.<\/p>\n\n<\/div>\n<div id=\"\" class=\"wpb_content_element bbg-single-image align-center\">\n    <figure class=\"bbg-single-image__figure\" style=\"max-width:100%\">\n                <img loading=\"lazy\" decoding=\"async\" width=\"979\" height=\"779\" src=\"https:\/\/assets.bbhub.io\/image\/v1\/resize?width=auto&amp;type=webp&amp;url=https:\/\/assets.bbhub.io\/professional\/sites\/41\/Exhibit-2.png\" class=\"bbg-single-image__image attachment-full\" alt=\"Sector Market Values for B500 Index\" title=\"Sector Market Values for B500 Index\" srcset=\"https:\/\/assets.bbhub.io\/image\/v1\/resize?width=auto&amp;type=webp&amp;url=https:\/\/assets.bbhub.io\/professional\/sites\/41\/Exhibit-2.png 979w, https:\/\/assets.bbhub.io\/image\/v1\/resize?width=auto&amp;type=webp&amp;url=https:\/\/assets.bbhub.io\/professional\/sites\/41\/Exhibit-2-552x439.png 552w, https:\/\/assets.bbhub.io\/image\/v1\/resize?width=auto&amp;type=webp&amp;url=https:\/\/assets.bbhub.io\/professional\/sites\/41\/Exhibit-2-800x637.png 800w, https:\/\/assets.bbhub.io\/image\/v1\/resize?width=auto&amp;type=webp&amp;url=https:\/\/assets.bbhub.io\/professional\/sites\/41\/Exhibit-2-768x611.png 768w, https:\/\/assets.bbhub.io\/image\/v1\/resize?width=auto&amp;type=webp&amp;url=https:\/\/assets.bbhub.io\/professional\/sites\/41\/Exhibit-2-136x108.png 136w\" sizes=\"auto, (max-width: 979px) 100vw, 979px\" \/>\n        \n            <\/figure>\n<\/div>\n\n<\/div>\n\n\n                    <\/div>\n    <\/section>\n<\/div>\n\n<div  class=\"bbg-row-container\">\n    <section class=\"bbg-row  text--black row-padding--top-none row-padding--bottom-none bbg-row--margin-top-compact bbg-row--margin-bottom-compact bbg-row--full-bg-bleed\" data-anchor='row-69f27b929d91d'>\n        \n        \n        <div\n            class=\"bbg-row--content\"\n                    >\n            \n            <div\n    class=\"bbg-column\"\n    style=\"\"\n    >\n    <div class=\"bbg-interstitial\" aria-label=\"interstitial\" tabindex=\"0\">\n\t<style>\n\t\t.bbg-interstitial #card_2.bbg-card_hasCta{\n\t\t\tbackground: url(https:\/\/assets.bbhub.io\/image\/v1\/resize?width=auto&amp;type=webp&amp;url=https:\/\/assets.bbhub.io\/professional\/sites\/41\/Interstitial_bg.png);\n\t\t\t\tbackground-repeat: no-repeat;\n\t\t\t\tbackground-position: center center;\n\t\t\t\tbackground-size: cover;\n\t\t\tpadding: 104px;\n\t\t\t\n\t\t\t\n\t\t}\n\t\t.bbg-interstitial #card_2.bbg-card_hasCta .bbg-card__content, .bbg-interstitial #card_2.bbg-card_hasCta .bbg-card__content p{\n\t\t\tcolor:white;\n\t\t}\n\t\t@media (max-width: 768px) {\n\t\t\t.bbg-interstitial #card_2.bbg-card_hasCta{\n\t\t\t\tpadding: 80px 32px;\n\t\t\t}\n\t\t}\n\t\t@media (max-width: 480px) {\n\t\t\t.bbg-interstitial #card_2.bbg-card_hasCta{\n\t\t\t\tpadding: 80px 18px;\n\t\t\t}\n\t\t}\n\t<\/style>\n\t<div class=\"wpb_content_element bbg-card  bbg-card-dark bbg-card_hasCta has_interstitial\" id=\"card_2\" data-card_type=\"no_image\">\n  \n  \n  <div class=\"bbg-card__innerwrapper\">\n    <div class=\"bbg-card__content\">\n      \n      \n                      <h3 class=\"bbg-card__title\">Tailored indices insights and invitations in your inbox<\/h3>\n      \n              <div class=\"bbg-card__wysiwyg bb-wysiwyg\"><p>Sign up<\/p>\n<\/div>\n          <\/div>\n\n          \n<div\n  id=\"cta_4305686188322210315\"\n  class=\"wpb_content_element bbg-cta icon icon-arrow\">\n  <style>\n    \n    \n    \n  <\/style>\n  <div\n    class=\"bbg-cta-link link-holder\"\n    data-links-type=\"cta-links\">\n    <p class=\"bbg-cta-p right\">\n      <a\n        class=\"bbg-cta-link link interstitial_cta\"\n        href=\"https:\/\/www.bloomberg.com\/professional\/explore\/indices-insights-tailored-to-your-interests\/\"\n        target=\"\"\n        rel=\"\"\n        data-section-name=\"\"\n                role=\"button\"\n        aria-label=\"Learn more\"\n        >\n                <\/a>\n    <\/p>\n  <\/div>\n<\/div>\n\n      <\/div>\n\n  <\/div>\n\n<\/div>\n\n\n<\/div>\n\n\n                    <\/div>\n    <\/section>\n<\/div>\n\n<div  class=\"bbg-row-container\">\n    <section class=\"bbg-row  text--black row-padding--top-compact row-padding--bottom-none bbg-row--full-bg-bleed\" data-anchor='row-69f27b92b0492'>\n        \n        \n        <div\n            class=\"bbg-row--content\"\n                    >\n            \n            <p><div\n    class=\"bbg-column bbg-column--width-2\"\n    style=\"\"\n    >\n    \n<\/div><div\n    class=\"bbg-column bbg-column--width-8\"\n    style=\"\"\n    >\n    <div\n\tclass=\"bb-wysiwyg\"\n\t\t>\n\t<h2>What the effective number of stocks reveals about market breadth<\/h2>\n<p>While top-N weights (e.g. top 5 or top 10) are commonly used to assess concentration, they focus only on the largest constituents. A more comprehensive concentration measure is the <strong>effective number of stocks\/sectors<\/strong>. It is calculated as the inverse of the sum of squared constituent weights. In the extreme case of a single-stock market, the effective number is 1. In a perfectly equal-weighted market of N stocks, the effective number equals N. This metric captures the full weight distribution, not just the top tier.<\/p>\n<p>Using this framework, we examine the effective number of stocks for the Bloomberg <a href=\"https:\/\/www.bloomberg.com\/professional\/products\/indices\/quote\/B3000T:IND\">B3000<\/a> and <a href=\"https:\/\/www.bloomberg.com\/professional\/products\/indices\/quote\/B500:IND\">B500<\/a> over the past three decades. The B3000 has historically exhibited an average effective number of 177. However, since its peak in 2015, effective number has declined materially, indicating a structurally narrow market despite a large nominal number of constituents.<\/p>\n\n<\/div>\n<div id=\"\" class=\"wpb_content_element bbg-single-image align-center\">\n    <figure class=\"bbg-single-image__figure\" style=\"max-width:100%\">\n                <img loading=\"lazy\" decoding=\"async\" width=\"975\" height=\"545\" src=\"https:\/\/assets.bbhub.io\/image\/v1\/resize?width=auto&amp;type=webp&amp;url=https:\/\/assets.bbhub.io\/professional\/sites\/41\/Exhibit-3.png\" class=\"bbg-single-image__image attachment-full\" alt=\"Market Cap Weighted Effective Number of Stocks\" title=\"Market Cap Weighted Effective Number of Stocks\" srcset=\"https:\/\/assets.bbhub.io\/image\/v1\/resize?width=auto&amp;type=webp&amp;url=https:\/\/assets.bbhub.io\/professional\/sites\/41\/Exhibit-3.png 975w, https:\/\/assets.bbhub.io\/image\/v1\/resize?width=auto&amp;type=webp&amp;url=https:\/\/assets.bbhub.io\/professional\/sites\/41\/Exhibit-3-552x309.png 552w, https:\/\/assets.bbhub.io\/image\/v1\/resize?width=auto&amp;type=webp&amp;url=https:\/\/assets.bbhub.io\/professional\/sites\/41\/Exhibit-3-800x447.png 800w, https:\/\/assets.bbhub.io\/image\/v1\/resize?width=auto&amp;type=webp&amp;url=https:\/\/assets.bbhub.io\/professional\/sites\/41\/Exhibit-3-768x429.png 768w, https:\/\/assets.bbhub.io\/image\/v1\/resize?width=auto&amp;type=webp&amp;url=https:\/\/assets.bbhub.io\/professional\/sites\/41\/Exhibit-3-192x108.png 192w\" sizes=\"auto, (max-width: 975px) 100vw, 975px\" \/>\n        \n            <\/figure>\n<\/div>\n\n<div\n\tclass=\"bb-wysiwyg\"\n\t\t>\n\t<p><span style=\"font-weight: 400;\">A similar analysis at the sector level (using Bloomberg BICS Level 1) reveals similar dynamics. With 11 sectors in total, the long-term average effective number of sectors has been approximately 8.4. Over the past decade, this measure has also trended downward, confirming that concentration is not merely stock-specific but extends across industry structure.<\/span><\/p>\n\n<\/div>\n<div id=\"\" class=\"wpb_content_element bbg-single-image align-center\">\n    <figure class=\"bbg-single-image__figure\" style=\"max-width:100%\">\n                <img loading=\"lazy\" decoding=\"async\" width=\"892\" height=\"551\" src=\"https:\/\/assets.bbhub.io\/image\/v1\/resize?width=auto&amp;type=webp&amp;url=https:\/\/assets.bbhub.io\/professional\/sites\/41\/Exhibit-4.png\" class=\"bbg-single-image__image attachment-full\" alt=\"Market Cap Weighted Effective Number of Sectors\" title=\"Market Cap Weighted Effective Number of Sectors\" srcset=\"https:\/\/assets.bbhub.io\/image\/v1\/resize?width=auto&amp;type=webp&amp;url=https:\/\/assets.bbhub.io\/professional\/sites\/41\/Exhibit-4.png 892w, https:\/\/assets.bbhub.io\/image\/v1\/resize?width=auto&amp;type=webp&amp;url=https:\/\/assets.bbhub.io\/professional\/sites\/41\/Exhibit-4-552x341.png 552w, https:\/\/assets.bbhub.io\/image\/v1\/resize?width=auto&amp;type=webp&amp;url=https:\/\/assets.bbhub.io\/professional\/sites\/41\/Exhibit-4-800x494.png 800w, https:\/\/assets.bbhub.io\/image\/v1\/resize?width=auto&amp;type=webp&amp;url=https:\/\/assets.bbhub.io\/professional\/sites\/41\/Exhibit-4-768x474.png 768w, https:\/\/assets.bbhub.io\/image\/v1\/resize?width=auto&amp;type=webp&amp;url=https:\/\/assets.bbhub.io\/professional\/sites\/41\/Exhibit-4-175x108.png 175w\" sizes=\"auto, (max-width: 892px) 100vw, 892px\" \/>\n        \n            <\/figure>\n<\/div>\n\n<div\n\tclass=\"bb-wysiwyg\"\n\t\t>\n\t<h2>Could sector rotation signal a turning point in market concentration?<\/h2>\n<p><span style=\"font-weight: 400;\">Interestingly, the behavior of these two metrics differs across historical episodes. During the dot-com bubble, both stock-level and sector-level effective breadth declined sharply and then recovered. During the Global Financial Crisis, however, the decline and subsequent rebound were far more pronounced at the stock level than at the sector level, highlighting the distinct structural nature of each crisis.<\/span><\/p>\n<p>As for the current period of elevated concentration, we do not claim foresight. The rise in concentration may reflect overvaluation similar to the late 1990s, albeit stretched over a longer horizon. Alternatively, it may represent a structural transformation driven by technological change and scale advantages that are more persistent. The truth could lie somewhere between these extremes.<\/p>\n<p>For investors who believe that valuation dispersion has played a role in the prolonged rise in concentration, history offers an important reminder: turning points in market breadth can be abrupt. Periods of extreme dominance have often been followed by sustained recoveries in effective breadth. The experience of the dot-com cycle illustrates this clearly \u2014 both the effective number of stocks and, even more notably, the effective number of sectors rebounded meaningfully once concentration peaked.<\/p>\n\n<\/div>\n<div id=\"\" class=\"wpb_content_element bbg-single-image align-center\">\n    <figure class=\"bbg-single-image__figure\" style=\"max-width:100%\">\n                <img loading=\"lazy\" decoding=\"async\" width=\"1016\" height=\"620\" src=\"https:\/\/assets.bbhub.io\/image\/v1\/resize?width=auto&amp;type=webp&amp;url=https:\/\/assets.bbhub.io\/professional\/sites\/41\/Exhibit-5.png\" class=\"bbg-single-image__image attachment-full\" alt=\"Market Cap Weighted Effective Number of Sectors in Recent Years\" title=\"Market Cap Weighted Effective Number of Sectors in Recent Years\" srcset=\"https:\/\/assets.bbhub.io\/image\/v1\/resize?width=auto&amp;type=webp&amp;url=https:\/\/assets.bbhub.io\/professional\/sites\/41\/Exhibit-5.png 1016w, https:\/\/assets.bbhub.io\/image\/v1\/resize?width=auto&amp;type=webp&amp;url=https:\/\/assets.bbhub.io\/professional\/sites\/41\/Exhibit-5-552x337.png 552w, https:\/\/assets.bbhub.io\/image\/v1\/resize?width=auto&amp;type=webp&amp;url=https:\/\/assets.bbhub.io\/professional\/sites\/41\/Exhibit-5-800x488.png 800w, https:\/\/assets.bbhub.io\/image\/v1\/resize?width=auto&amp;type=webp&amp;url=https:\/\/assets.bbhub.io\/professional\/sites\/41\/Exhibit-5-100x60.png 100w, https:\/\/assets.bbhub.io\/image\/v1\/resize?width=auto&amp;type=webp&amp;url=https:\/\/assets.bbhub.io\/professional\/sites\/41\/Exhibit-5-768x469.png 768w, https:\/\/assets.bbhub.io\/image\/v1\/resize?width=auto&amp;type=webp&amp;url=https:\/\/assets.bbhub.io\/professional\/sites\/41\/Exhibit-5-177x108.png 177w\" sizes=\"auto, (max-width: 1016px) 100vw, 1016px\" \/>\n        \n            <\/figure>\n<\/div>\n\n<div\n\tclass=\"bb-wysiwyg\"\n\t\t>\n\t<h2>How risk-based sector concentration differs from market-cap concentration<\/h2>\n<p>The first half of 2025 also saw a notable \u2014 though ultimately temporary \u2014 easing in concentration following the sharp market repricing (Exhibit 5). The recent improvement in effective breadth naturally invites comparison. However, a closer look at sector weight changes reveals meaningful structural differences in the underlying rotation.<\/p>\n<p>Technology, the largest sector, was hit hardest in both episodes. In the first half of 2025, consumer discretionary was the second hardest hit, reflecting the tariff-driven nature of the correction, while more tariff-resistant sectors gained relative weight.<\/p>\n<p>In recent months, by contrast, the rotation has looked more like a broad shift away from technology toward more traditional industrial sectors. Financials have been an exception, pressured by concerns surrounding private credit \u2014 more a spillover effect than a primary driver. Given the ongoing reassessment of AI and related themes, the current shift could evolve into a more durable rotation, potentially marking the early stages of a more persistent normalization in market structure.<\/p>\n<p>Taking the analysis a step further, we examine sector-level risk contributions and derive an \u201ceffective number of sectors\u201d on that basis. This measure is even lower than the one based purely on market-cap weights, suggesting that larger sectors carry disproportionately higher risk and thereby amplify concentration when size and volatility are considered jointly.<\/p>\n<p>Moreover, the recent episode reflects a smaller improvement in risk-based breadth than the one observed in the first half of 2025. In other words, technology\u2019s dominance from a risk perspective is now even more pronounced than it was then.<\/p>\n<p>Taken together, this indicates that the current shift is less a broad-based macro-driven correction and more a concentrated move led by a single sector. The recent easing in market-cap concentration is therefore partially offset by an intensification in risk concentration. While risk concentration tends to be cyclical and mean-reverting, shifts in market-cap concentration are typically more enduring, reflecting deeper changes in market structure.<\/p>\n\n<\/div>\n<div id=\"\" class=\"wpb_content_element bbg-single-image align-center\">\n    <figure class=\"bbg-single-image__figure\" style=\"max-width:100%\">\n                <img loading=\"lazy\" decoding=\"async\" width=\"1010\" height=\"318\" src=\"https:\/\/assets.bbhub.io\/image\/v1\/resize?width=auto&amp;type=webp&amp;url=https:\/\/assets.bbhub.io\/professional\/sites\/41\/Exhibit-6.png\" class=\"bbg-single-image__image attachment-full\" alt=\"Comparison of Effective Number of Sectors\" title=\"Comparison of Effective Number of Sectors\" srcset=\"https:\/\/assets.bbhub.io\/image\/v1\/resize?width=auto&amp;type=webp&amp;url=https:\/\/assets.bbhub.io\/professional\/sites\/41\/Exhibit-6.png 1010w, https:\/\/assets.bbhub.io\/image\/v1\/resize?width=auto&amp;type=webp&amp;url=https:\/\/assets.bbhub.io\/professional\/sites\/41\/Exhibit-6-552x174.png 552w, https:\/\/assets.bbhub.io\/image\/v1\/resize?width=auto&amp;type=webp&amp;url=https:\/\/assets.bbhub.io\/professional\/sites\/41\/Exhibit-6-800x252.png 800w, https:\/\/assets.bbhub.io\/image\/v1\/resize?width=auto&amp;type=webp&amp;url=https:\/\/assets.bbhub.io\/professional\/sites\/41\/Exhibit-6-768x242.png 768w, https:\/\/assets.bbhub.io\/image\/v1\/resize?width=auto&amp;type=webp&amp;url=https:\/\/assets.bbhub.io\/professional\/sites\/41\/Exhibit-6-192x60.png 192w\" sizes=\"auto, (max-width: 1010px) 100vw, 1010px\" \/>\n        \n            <\/figure>\n<\/div>\n\n<div id=\"\" class=\"wpb_content_element bbg-single-image align-center\">\n    <figure class=\"bbg-single-image__figure\" style=\"max-width:100%\">\n                <img loading=\"lazy\" decoding=\"async\" width=\"953\" height=\"704\" src=\"https:\/\/assets.bbhub.io\/image\/v1\/resize?width=auto&amp;type=webp&amp;url=https:\/\/assets.bbhub.io\/professional\/sites\/41\/Exhibit-7-1.png\" class=\"bbg-single-image__image attachment-full\" alt=\"Comparison of Sector Weights Change\" title=\"Comparison of Sector Weights Change\" srcset=\"https:\/\/assets.bbhub.io\/image\/v1\/resize?width=auto&amp;type=webp&amp;url=https:\/\/assets.bbhub.io\/professional\/sites\/41\/Exhibit-7-1.png 953w, https:\/\/assets.bbhub.io\/image\/v1\/resize?width=auto&amp;type=webp&amp;url=https:\/\/assets.bbhub.io\/professional\/sites\/41\/Exhibit-7-1-552x408.png 552w, https:\/\/assets.bbhub.io\/image\/v1\/resize?width=auto&amp;type=webp&amp;url=https:\/\/assets.bbhub.io\/professional\/sites\/41\/Exhibit-7-1-800x591.png 800w, https:\/\/assets.bbhub.io\/image\/v1\/resize?width=auto&amp;type=webp&amp;url=https:\/\/assets.bbhub.io\/professional\/sites\/41\/Exhibit-7-1-768x567.png 768w, https:\/\/assets.bbhub.io\/image\/v1\/resize?width=auto&amp;type=webp&amp;url=https:\/\/assets.bbhub.io\/professional\/sites\/41\/Exhibit-7-1-146x108.png 146w\" sizes=\"auto, (max-width: 953px) 100vw, 953px\" \/>\n        \n            <\/figure>\n<\/div>\n\n<div id=\"\" class=\"wpb_content_element bbg-single-image align-center\">\n    <figure class=\"bbg-single-image__figure\" style=\"max-width:100%\">\n                <img loading=\"lazy\" decoding=\"async\" width=\"2322\" height=\"1750\" src=\"https:\/\/assets.bbhub.io\/image\/v1\/resize?width=auto&amp;type=webp&amp;url=https:\/\/assets.bbhub.io\/professional\/sites\/41\/Exhibit-8-Comparison-of-Sector-Risk-Contribution-Change-based-on-MAC3-Factor-Risk-Model.png\" class=\"bbg-single-image__image attachment-full\" alt=\"Exhibit 8 - Comparison of Sector Risk Contribution Change based on MAC3 Factor Risk Model[\" title=\"Exhibit 8 - Comparison of Sector Risk Contribution Change based on MAC3 Factor Risk Model[\" srcset=\"https:\/\/assets.bbhub.io\/image\/v1\/resize?width=auto&amp;type=webp&amp;url=https:\/\/assets.bbhub.io\/professional\/sites\/41\/Exhibit-8-Comparison-of-Sector-Risk-Contribution-Change-based-on-MAC3-Factor-Risk-Model.png 2322w, https:\/\/assets.bbhub.io\/image\/v1\/resize?width=auto&amp;type=webp&amp;url=https:\/\/assets.bbhub.io\/professional\/sites\/41\/Exhibit-8-Comparison-of-Sector-Risk-Contribution-Change-based-on-MAC3-Factor-Risk-Model-552x416.png 552w, https:\/\/assets.bbhub.io\/image\/v1\/resize?width=auto&amp;type=webp&amp;url=https:\/\/assets.bbhub.io\/professional\/sites\/41\/Exhibit-8-Comparison-of-Sector-Risk-Contribution-Change-based-on-MAC3-Factor-Risk-Model-800x603.png 800w, https:\/\/assets.bbhub.io\/image\/v1\/resize?width=auto&amp;type=webp&amp;url=https:\/\/assets.bbhub.io\/professional\/sites\/41\/Exhibit-8-Comparison-of-Sector-Risk-Contribution-Change-based-on-MAC3-Factor-Risk-Model-768x579.png 768w, https:\/\/assets.bbhub.io\/image\/v1\/resize?width=auto&amp;type=webp&amp;url=https:\/\/assets.bbhub.io\/professional\/sites\/41\/Exhibit-8-Comparison-of-Sector-Risk-Contribution-Change-based-on-MAC3-Factor-Risk-Model-1536x1158.png 1536w, https:\/\/assets.bbhub.io\/image\/v1\/resize?width=auto&amp;type=webp&amp;url=https:\/\/assets.bbhub.io\/professional\/sites\/41\/Exhibit-8-Comparison-of-Sector-Risk-Contribution-Change-based-on-MAC3-Factor-Risk-Model-2048x1543.png 2048w, https:\/\/assets.bbhub.io\/image\/v1\/resize?width=auto&amp;type=webp&amp;url=https:\/\/assets.bbhub.io\/professional\/sites\/41\/Exhibit-8-Comparison-of-Sector-Risk-Contribution-Change-based-on-MAC3-Factor-Risk-Model-143x108.png 143w\" sizes=\"auto, (max-width: 2322px) 100vw, 2322px\" \/>\n        \n            <\/figure>\n<\/div>\n\n<div\n\tclass=\"bb-wysiwyg\"\n\t\t>\n\t<p><span class=\"TextRun SCXW70507539 BCX0\" lang=\"EN-US\" xml:lang=\"EN-US\" data-contrast=\"auto\"><span class=\"NormalTextRun SCXW70507539 BCX0\" data-ccp-parastyle=\"Normal (Web)\">While the answer will only become clear with time, investors need not hold a definitive view to consider the implications. In environments where concentration risk has been elevated,\u00a0<\/span><span class=\"NormalTextRun SCXW70507539 BCX0\" data-ccp-parastyle=\"Normal (Web)\">investors may consider\u00a0<\/span><span class=\"NormalTextRun SCXW70507539 BCX0\" data-ccp-parastyle=\"Normal (Web)\">whether traditional market-cap-weighted benchmarks\u00a0<\/span><span class=\"NormalTextRun SCXW70507539 BCX0\" data-ccp-parastyle=\"Normal (Web)\">remain<\/span><span class=\"NormalTextRun SCXW70507539 BCX0\" data-ccp-parastyle=\"Normal (Web)\">\u00a0the most effective representation of the opportunity set \u2014 or whether alternative weighting approaches can offer a more balanced exposure when breadth begins to shift.<\/span><\/span><span class=\"EOP Selected SCXW70507539 BCX0\" data-ccp-props=\"{&quot;134233117&quot;:true,&quot;134233118&quot;:true,&quot;201341983&quot;:0,&quot;335559740&quot;:240}\">\u00a0<\/span><\/p>\n\n<\/div>\n\n<\/div>\n\n\n                    <\/div>\n    <\/section>\n<\/div>\n\n<div  class=\"bbg-row-container\">\n    <section class=\"bbg-row  text--black row-padding--top-none bbg-row--full-bg-bleed\" data-anchor='row-69f27b92bd30f'>\n        \n        \n        <div\n            class=\"bbg-row--content\"\n                    >\n            \n            <p><div\n    class=\"bbg-column bbg-column--width-2\"\n    style=\"\"\n    >\n    \n<\/div><div\n    class=\"bbg-column bbg-column--width-8\"\n    style=\"\"\n    >\n    <div class=\"bbg-accordion transparent\">\n\t<input type=\"checkbox\"  id=\"bbg-accordion-toggle-69f27b92c2485\">\n\t<div class=\"bbg-accordion-parent\" data-accordion-toggle aria-expanded=\"false\">\n\t\t<label class=\"bbg-accordion-label\" for=\"bbg-accordion-toggle-69f27b92c2485\">\n\t\t\t\t<h5 class=\"bbg-accordion-title\" data-label=\"Disclaimer\">\n\t\tDisclaimer\n\t<\/h5>\n\n\t\t\t\t\t<\/label>\n\t<\/div>\n\t<div class=\"bbg-accordion-content\">\n\t\t<div class=\"bb-wysiwyg\">\n\t<p style=\"font-size: 16px !important; line-height: 24px;\">Bloomberg does not represent that the quantitative models, analytic tools and\/or other information (\u201cContent\u201d) referenced in this publication (including information obtained from third party sources) is accurate, complete or error free, and it should not be relied upon as such, nor does Bloomberg guarantee the timeliness, reliability, performance, continued availability, or currency of any Content. 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