Understanding the GICS Classification System
How Does the GICS Classification System Work?
The GICS classification system is the backbone of modern sector investing, providing a rigorous, globally consistent framework for organizing every publicly traded company into a four-level hierarchy from broad sector down to specific sub-industry. Developed jointly by MSCI and S&P Dow Jones Indices in 1999, GICS became the dominant standard for institutional investors worldwide, replacing a fragmented landscape of competing classification schemes with a single authoritative framework that is maintained, updated, and applied consistently across markets and geographies.
Quick definition: GICS (Global Industry Classification Standard) is a four-level hierarchical taxonomy that assigns every publicly traded company to exactly one of 11 sectors, based on its principal business activity, enabling consistent cross-company and cross-market comparisons.
Key takeaways
- GICS has four levels: 11 sectors, 25 industry groups, 74 industries, and 163 sub-industries
- Every company is assigned to exactly one sub-industry, which determines its sector membership
- Classifications are reviewed annually and periodically reclassified based on business evolution
- The 2018 reclassification that created Communication Services is the most consequential recent change
- Understanding GICS levels helps investors work at the appropriate granularity for their analysis
The four levels of the GICS hierarchy
The GICS taxonomy works from the general to the specific, with each level subdividing the level above it. At the broadest level, 11 sectors capture the major segments of the economy: Information Technology, Communication Services, Consumer Discretionary, Consumer Staples, Healthcare, Financials, Industrials, Energy, Materials, Utilities, and Real Estate.
Below sectors sit 25 industry groups, which provide a more granular view. The Healthcare sector contains three industry groups: Health Care Equipment and Services; Pharmaceuticals, Biotechnology and Life Sciences; and Health Care Providers and Services. The Financials sector contains four industry groups: Banks; Financial Services; Insurance; and Diversified Financials.
The third level, industries, provides 74 categories. Within the Information Technology sector's Software and Services industry group, you find industries including Application Software, Systems Software, and IT Consulting and Other Services. At this level, comparisons become more analytically rigorous because companies in the same industry typically compete directly with each other.
The fourth and most granular level, sub-industries, comprises 163 categories. These allow the most precise comparisons. "Semiconductor Equipment" is a sub-industry distinct from "Semiconductors" within the same sector; the equipment makers have completely different business models, customers, and financial characteristics than the chipmakers they serve. Understanding sub-industry distinctions matters when building ETFs, running quantitative screens, or performing deep fundamental analysis.
How companies are classified
Classification is based on the primary business activity of the company, defined as the segment generating the largest share of revenues. For most companies, this is straightforward: an oil exploration company is clearly in the Energy sector's Upstream Oil and Gas sub-industry. But for diversified companies, the assignment requires judgment.
A technology conglomerate that generates 60% of its revenues from hardware and 40% from software services would typically be classified in the hardware segment. If its business mix shifted and software revenues grew to 70%, a GICS reclassification could follow — often after a formal review process. These reclassifications are announced months in advance to give index funds and ETFs time to adjust their holdings without disruptive forced trades.
The SEC requires publicly traded companies to disclose segment revenues, which provides the empirical basis for GICS assignment. Investors who want to understand why a specific company is classified in a particular sub-industry should review its SEC filings at sec.gov to see how the company describes its own business segments.
The 2018 reclassification: a case study
The most consequential GICS change in recent memory occurred in September 2018, when MSCI and S&P Dow Jones Indices reclassified a substantial group of companies from the Information Technology and Consumer Discretionary sectors into a redesigned Telecommunication Services sector, renamed Communication Services.
Before the change, Alphabet (Google) and Facebook (Meta) sat in the Information Technology sector, which they had joined as internet companies in the early days of the GICS framework. As their business models evolved — Google into search advertising and cloud services, Facebook into social media advertising — the companies' economic characteristics diverged significantly from traditional software and hardware businesses.
Netflix, previously in Consumer Discretionary, also moved to Communication Services, reflecting its position as a content and streaming platform. The combined effect was dramatic: the IT sector's market cap dropped by hundreds of billions of dollars, and Communication Services was transformed from a stagnant telecom backwater into one of the most dynamic sectors in the index. Investors who had built sector allocations on pre-2018 data found that the historical return characteristics of Communication Services were essentially irrelevant to the new sector's composition.
This episode illustrates a general principle: GICS classifications reflect economic reality at a point in time and can change as industries evolve. Investors who use historical sector data without understanding what was actually in the sector during the measurement period may draw misleading conclusions.
Decision tree
Industry groups and their analytical utility
For most individual investors and portfolio managers, working at the sector level provides sufficient granularity for allocation decisions. But professionals who manage portfolios with specific risk mandates often work at the industry group level.
The 25 industry groups allow more precise hedging and relative-value positioning. Within the Healthcare sector, an investor who believes pharmaceutical patent expirations will hurt large pharma while medical device companies remain strong can overweight the "Health Care Equipment and Supplies" industry group while underweighting "Pharmaceuticals." This level of precision is impossible at the sector level but becomes actionable at the industry group level.
Similarly, within Financials, an investor who expects rising interest rates to benefit banks but hurt insurance companies can overweight the "Banks" industry group while underweighting "Insurance" — a tactical view expressed within a single sector.
Sub-industries as the analyst's working unit
Equity analysts who cover specific companies typically think at the sub-industry level because the most relevant peer comparisons occur between companies in the same sub-industry. A semiconductor equipment analyst compares Applied Materials to ASML and Lam Research — all in the Semiconductor Equipment sub-industry — rather than to Nvidia or Intel, which are in the Semiconductors sub-industry. The financial ratios, growth drivers, and competitive dynamics that matter for the comparison are most similar within sub-industries.
The 163 sub-industries include some that are very small: the "Tobacco" sub-industry in Consumer Staples contains only a handful of major public companies, and certain specialty sub-industries may contain only one or two names. At the other extreme, "Application Software" and "Diversified Banks" contain dozens of large public companies each.
Real-world examples
The classification of Amazon illustrates the complexity of GICS assignment for diversified businesses. Despite generating enormous revenues from its Amazon Web Services (AWS) cloud business, which would logically place it in Information Technology, Amazon is classified in Consumer Discretionary because its retail and marketplace revenues constitute the largest segment of its overall business. This means that AWS — a cloud infrastructure giant — lives inside the Consumer Discretionary sector, creating notable anomalies for investors who try to analyze "technology exposure" through sector data alone.
Tesla's reclassification from Consumer Discretionary (as an automaker) to its continued placement in that sector despite evolving into an energy storage and autonomous driving technology company is another example. The GICS framework classifies by primary revenue source, not by the investor narrative around the company.
Common mistakes
Assuming sub-industry peers are identical businesses. Two companies in the same GICS sub-industry can have dramatically different financial profiles. Within "Application Software," a company with 80% recurring revenue from long-term SaaS contracts has vastly different risk characteristics than one selling perpetual licenses with lumpy revenue. Sub-industry classification is a starting point for comparison, not a conclusion.
Relying on historical sector data without checking for reclassifications. If you are comparing the Communication Services sector's current valuation to its 10-year average, but the sector's composition changed fundamentally in 2018, the comparison is misleading. Always verify what was in the sector during any historical measurement period before drawing conclusions.
Ignoring the fourth GICS level. Many retail investors stop at the sector level, but sub-industry data is where the most actionable analysis lives. The difference between investing in the Healthcare sector broadly versus focusing on the Managed Care Organizations sub-industry represents a completely different set of return drivers, risks, and valuation frameworks.
Treating GICS as an objective scientific classification. GICS classifications involve judgment, particularly for diversified businesses. Two reasonable analysts could classify the same company differently. Understanding the judgment involved helps investors use GICS as a tool rather than treating it as immutable truth.
FAQ
Who maintains and updates the GICS classification system?
GICS is maintained jointly by MSCI and S&P Dow Jones Indices. They conduct annual consultations with market participants to solicit feedback on proposed classification changes, and periodic structural reviews assess whether the overall framework adequately reflects the current economy.
How often are individual companies reclassified?
Individual companies are reclassified when there is a significant change in their business model or revenue composition. Reclassifications are announced with several months of advance notice and are implemented simultaneously with index rebalancing to minimize disruption to index-tracking funds.
Is GICS the only sector classification framework?
No. Other frameworks include the Industry Classification Benchmark (ICB) used by FTSE Russell and some European indices, and the North American Industry Classification System (NAICS) used by the US government for economic statistics. GICS is dominant among institutional equity investors, but these alternatives exist and occasionally produce different classifications for the same company.
Does a company's GICS classification affect its stock price?
Indirectly, yes. Inclusion in a high-weight sector can increase the demand for a stock from sector-specific ETFs and investors with sector mandates. When Alphabet moved from IT to Communication Services in 2018, Communication Services ETFs were required to purchase Alphabet shares, while some IT ETFs were required to sell. These mechanical flows can temporarily affect stock prices.
Where can I look up a company's GICS classification?
MSCI and S&P Dow Jones Indices maintain classification tools on their websites. Most financial data providers — Bloomberg, FactSet, Morningstar — display GICS classifications in their security profiles. The SEC's EDGAR database also contains company filings that describe business segments which typically align with GICS classification.
How does GICS handle fintech companies?
Fintech companies are typically classified in Financials (if they primarily earn revenue from financial services) or in Information Technology (if they primarily earn revenue from software and technology services sold to financial institutions). The line can be blurry, and high-profile fintech companies have sometimes been classified differently than investors expected.
Related concepts
- Introduction to Market Sectors
- Sector vs Industry Distinction
- Sector Benchmarks and Indices
- Communication Services Overview
- Information Technology Overview
- Getting Started with Sector Investing
Summary
The GICS classification system is the infrastructure of sector investing, providing the consistent, globally applied framework that allows investors to group companies by economic characteristics, build sector indices, and make meaningful cross-company comparisons. Its four levels — sector, industry group, industry, and sub-industry — serve different analytical purposes. Periodic reclassifications ensure the framework reflects the evolving economy, but they require investors to verify what was in a sector during any historical measurement period before drawing comparative conclusions. Understanding GICS is not an academic exercise; it determines which ETF holds which stock, which benchmarks are being tracked, and what "sector exposure" actually means in a specific portfolio.