05 · Indexes and Sectors: The Market's Ruler and Map
You often hear "the market rose 2% today" or "the CSI 300 fell". That "market" is not a single stock but an index. An index weight-averages the moves of hundreds of stocks into one line — the "ruler" for observing the market; industry sectors are the "map" that groups stocks by business.
This article explains: how an index is calculated, what styles the major A-share/HK/US/global indexes each represent, industry sectors and style classification, sector rotation and the Merrill Lynch Investment Clock, and how to choose between "index investing vs individual stocks".
⚠️ Risk Warning
This article is for learning and research only and does not constitute investment advice. Constituent counts, weight ratios, rebalancing dates, and point ranges mentioned here are generic teaching descriptions — always defer to the latest methodologies and announcements of each index company (CSI Indexes, CNI Indexes, Hang Seng Indexes, S&P Dow Jones Indices, MSCI, etc.). For index funds' tracking error, fees, and subscription/redemption rules, defer to the fund contracts.
What Is an Index
An index is not a "commodity" — it is the product of a set of stock-selection and weighting rules. Three things are enough to understand it:
Weighting: market-cap weighted vs equal weighted
| Method | Rule | Characteristics | Examples |
|---|---|---|---|
| Market-cap weighted | Stock weight ∝ market cap | Big companies move the index; market swings are mostly decided by large names | CSI 300, S&P 500, Hang Seng Index |
| Equal weighted | Every stock has the same weight | Small names' influence is amplified; more volatile, higher elasticity | CSI 500 Equal Weight, S&P 500 Equal Weight |
| Price weighted | Weight ∝ share price | High-priced stocks dominate (unscientific but a historical legacy) | Dow Jones Industrial Average |
- Market-cap weighting is the absolute mainstream: its virtue is "buying the index = buying the whole market in proportion to cap", and big companies' share naturally mirrors the economy's structure.
- Equal-weighted indexes usually outperform in mid-to-late bull markets (small names catch up) but fare worse in drawdowns.
Constituents and rebalancing
- Constituents: index companies select members by rules (market-cap rank, liquidity, industry spread). For example, CSI 300 = the top 300 Shanghai/Shenzhen stocks by cap (with liquidity screening and other details).
- Periodic rebalancing: most indexes adjust constituents every six months (effective after the close on the second Friday of June/December); CSI Indexes also runs "sample maintenance" for suspensions, delistings, and other anomalies.
- Rebalancing effects: newly added names are bought heavily by tracking funds (index funds must match weights) while removed names get dumped — an observable short-term "rebalancing trade".
- Weight caps: to keep any single stock from dominating, many indexes cap weights (e.g., max 10% per stock); per the latest methodology.
Price index vs total return index
- Price index: counts only price changes, excluding dividends (e.g., the commonly quoted SSE Composite and CSI 300 levels).
- Total return index: assumes dividends are reinvested; higher long-term return (the long-run annualized gap is roughly the dividend yield, about 2%-3% for A-shares, per latest data).
- Holding an index fund actually delivers "close to total return" — mind the basis difference when comparing against quoted index levels.
The A-Share Index System
The A-share index family is layered by "cap gradient", from mega-cap down to micro-cap. Memorize the gradient first, then what each name represents.
| Index | Constituents | Style | One-line mnemonic |
|---|---|---|---|
| SSE Composite (000001) | All stocks listed on the Shanghai exchange | The whole market's "veteran name card" | What old-timers call "the market" |
| CSI 300 (000300) | Top 300 Shanghai/Shenzhen by cap | Large-cap blue chips, core assets | "The A-share S&P 500" |
| SSE 50 (000016) | The 50 largest Shanghai names by cap | Mega-cap, heavy financials | "The elephant camp" |
| CSI 500 (000905) | Ranks 301-800 after excluding CSI 300 | Mid-cap growth, industry-balanced | "The mid-cap main force" |
| CSI 1000 (000852) | Ranks 801-1800 after excluding the top 800 | Small-cap themes, volatile | "The small-cap thermometer" |
| CNI 2000 (399303) | Roughly ranks 1001-3000 market-wide | Micro/small caps, hot-money territory | "The micro-cap weathervane" |
| ChiNext Index (399006) | Top 100 ChiNext by cap | Growth, heavy new-energy/pharma weight | "The innovative growth board" |
| STAR 50 (000688) | Top 50 STAR Market by cap | Hard tech, heavy semiconductors | "The domestic-substitution weathervane" |
| BSE 50 (899050) | Top 50 Beijing Stock Exchange by cap | "Little giant" small caps | "The BSE flagship" |
A few practical insights
- The SSE Composite ≠ all of A-shares: it covers only the Shanghai exchange, with heavy bank and oil weights — often "the index didn't fall, the stocks got slaughtered".
⚠️ The SSE Composite is not all of A-shares
The SSE Composite ≠ all of A-shares: it covers only the Shanghai exchange, with heavy bank and oil weights — often "the index didn't fall, the stocks got slaughtered". For A-share broad-based exposure, CSI 300 tracking funds come first; don't judge everything by the SSE Composite.
- CSI 300 is the institutional benchmark: public funds, insurers, and foreign money mostly benchmark against CSI 300 — prefer funds tracking it for broad A-share exposure.
- CSI 1000 / CNI 2000 map to index futures/options: CFFEX IC and IM are tied to CSI 500 and CSI 1000, so small-cap styles can be hedged directly (see 03 - Futures / 04 - Futures Products).
- Style rotation: large caps (300/50) and small/mid caps (500/1000) often sit on a seesaw — loose liquidity and high risk appetite favor small caps; a zero-sum game of existing funds and risk-off favor large caps.
HK Stock Indexes
| Index | Constituents | Style |
|---|---|---|
| Hang Seng Index (HSI) | About the 80 largest main-board HK names (formerly 33, since expanded; per latest methodology) | HK large-cap blue chips, heavy financials + tech |
| Hang Seng Tech Index (HSTECH) | The top 30 tech firms listed in HK | Internet/tech growth, more volatile than HSI |
| Hang Seng China Enterprises Index (HSCEI) | Mainland Chinese firms listed in HK | The observation window for "China concepts coming home" |
- HSI is the "pricing anchor of HKD assets", tied to both mainland fundamentals and dollar liquidity: HK stocks are "a dollar-priced market for offshore renminbi assets" — foreign flows matter far more than for A-shares.
- Hang Seng Tech correlates fairly highly with the Nasdaq and is often treated as dual exposure to "China tech + dollar liquidity".
US Stock Indexes
| Index | Constituents | Style |
|---|---|---|
| Dow Jones Industrial Average (DJIA) | 30 blue chips, price weighted | Vintage industrial blue chips, "America's business card" |
| S&P 500 (SPX) | ~500 large companies, cap weighted | The core of US large caps, the global asset "barometer" |
| Nasdaq 100 (NDX) | Top 100 non-financial Nasdaq names by cap | Tech giants: Apple, Microsoft, Nvidia, etc. |
| Russell 2000 (RUT) | The smallest 2,000 of the Russell 3000 | Small caps, "America's domestic-demand thermometer" |
- The S&P 500 is "the global benchmark": the allocation hub for pensions, sovereign funds, and global ETFs; S&P 500 futures are the deepest equity index contract in the world.
- Large/small cap divergence signal: a strengthening Russell 2000 / S&P 500 ratio often signals rising "recovery expectations + cut expectations" (small caps are more rate-sensitive); a weakening ratio means money is crowding into big tech.
💡 The Nasdaq is the most rate-sensitive
The Nasdaq 100 is tightly bound to the growth style and takes the biggest valuation pressure when rates rise. When rates climb, the discounted value of growth stocks' distant cash flows gets cut and the Nasdaq usually falls more than the Dow — in hiking cycles, tech is slaughtered first.
Major Global Indexes
| Index | Country/Region | One-line character |
|---|---|---|
| Nikkei 225 | Japan | 225 blue chips, price weighted; the yen-asset weathervane, strong recently on the "Japan discount" revaluation |
| Germany DAX | Germany | ~40 blue chips including VW/Siemens; the eurozone manufacturing bellwether |
| FTSE 100 | UK | 100 large caps, heavy energy and financials; strongly correlated with oil and sterling |
| France CAC 40 | France | 40 blue chips, heavy luxury weight (LVMH etc.), a clear consumer flavor |
| India SENSEX | India | 30 Bombay Exchange blue chips; the EM demographic-dividend play with a strong long-term trend |
| Korea KOSPI | Korea | Extreme Samsung/SK Hynix weight; a leading gauge of the "global semiconductor cycle" |
| Vietnam VN30 | Vietnam | Top 30 Ho Chi Minh Exchange caps; retail-driven, volatile, the ASEAN newcomer |
| Taiwan Weighted Index (TWSE) | Taiwan, China | TSMC alone dominates; the "ultimate weathervane" of the semiconductor cycle |
| Singapore STI | Singapore | ~30 large caps dominated by banks/property/REITs; a steady emerging market |
| Brazil IBOVESPA | Brazil | Heavy commodity (mining/agriculture) weight; resonates with iron ore and soybean moves |
| Russia MOEX | Russia | Extreme energy weight; violently linked to sanctions and the exchange rate |
- The core use of global indexes is not "buy them all" but cross-comparing economic strength: when US PMI, European manufacturing, and China property all stall together, commodities and equities usually fall in sympathy.
Industry Sector Classification and Styles
SW Level-1 industries (examples)
The most used domestic industry classification is the SW (Shenwan) classification (the CSRC and CITIC classifications also exist). SW Level-1 has 31 industries (per the latest version); common ones:
| Industry | Representative companies (examples) | Driving logic |
|---|---|---|
| Banks | ICBC, CMB | Rates, net interest margin, asset quality |
| Non-bank financials | CITIC Securities, Ping An | Market turnover, rates, premiums |
| Food & beverage | Moutai, Yili | Consumption cycle, cash flow |
| Pharma & biotech | Hengrui, Mindray | Policy (centralized procurement), innovation cycles |
| Electronics | Luxshare, BOE | Global semiconductor/consumer-electronics cycles |
| Power equipment | CATL, LONGi | New-energy cycle, exports |
| Computer | Yonyou, Kingsoft | IT innovation (Xinchuang), AI orders |
| Automobiles | BYD, Great Wall | Sales volumes, price wars, going global |
| Real estate | Poly, Vanke | Policy easing, sales data |
| Coal / petrochemicals | China Shenhua, PetroChina | Commodity prices, dividend yield |
| Nonferrous metals | Zijin Mining, Ganfeng Lithium | Commodity prices, new-energy demand |
| Defense | AVIC Shenyang Aircraft, AECC | Defense budgets, orders, event-driven |
Style classification: growth / value / large cap / small cap
Style is how investors "tag" stocks, and style rotation is one of the most visible regularities in A-shares.
| Dimension | Growth style | Value style |
|---|---|---|
| Focus metrics | Revenue/profit growth, penetration | Low PE/PB, high dividend yield |
| Representative industries | Semiconductors, new energy, pharma | Banks, coal, utilities |
| Favorable environment | Loose liquidity, rate cuts, high risk appetite | Economic uncertainty, high rates, risk-off |
| Risks | Violent de-rating in drawdowns | Long-term "value trap" risk |
- The large/small cap axis is orthogonal to the growth/value axis: they combine into the four quadrants "large-cap growth (Moutai), large-cap value (banks), small-cap growth (theme stocks), small-cap value (low-priced cyclicals)".
- Common gauges: the CSI 800 value/growth ratio, the CSI 300 vs CSI 1000 ratio, and the relative strength of dividend indexes (the value proxy) versus growth ETFs.
Sector Rotation and the Merrill Lynch Investment Clock
The rotation phenomenon
- A-share industry returns show clear rotation: for a while liquor and pharma lead, then coal and power, then AI tech — "all sectors rising and falling together" is rare.
- Three forces drive the rotation:
- The macro cycle: in recovery, cyclicals (nonferrous, chemicals) rise first; in overheating, upstream resources (coal, oil) are strongest; in recession, defensives (utilities, pharma, consumer staples) hold up best.
- Industry cycles: policy-born mainlines (new energy, AI, Xinchuang) can run 1-3 years independent of the macro cycle.
- Money and sentiment: public fund launches, northbound flows, and hot-money theme switches drive short-term style strength.
The Merrill Lynch Investment Clock (brief)
The clock slices the economy into four phases along "growth + inflation" and ranks assets accordingly (a theoretical model; reality often skips or repeats phases):
| Phase | Growth | Inflation | Favored assets |
|---|---|---|---|
| Recovery | ↑ | ↓ | Stocks (cyclical growth) |
| Overheating | ↑ | ↑ | Commodities (energy, nonferrous) |
| Stagflation | ↓ | ↑ | Cash, gold (stocks and bonds both hit) |
| Recession | ↓ | ↓ | Bonds (falling rates) |
- Practical revision: China's A-shares are heavily policy-driven and the clock often "fails" there; more useful domestically are the two leading gauges "excess liquidity = money growth − inflation" and "aggregate financing/credit impulse".
- See 08 - Macro Economy and Markets, section "The Four Phases of the Economic Cycle", for more.
Index Investing vs Individual Stocks
| Dimension | Index investing (ETF/index funds) | Buying individual stocks |
|---|---|---|
| Risk | Diversified; a single blow-up has limited impact | Concentrated; a delisting/scandal can zero the position |
| Skill required | Only judge "market/style direction" | Must research company fundamentals |
| Cost | Low management fees (broad-based typically 0.15%-0.5%, per latest) | No management fee but trading commissions and stamp duty |
| Return ceiling | Averaged; hard to hit home runs | Can far exceed the index (or far underperform) |
| Suits | Most ordinary people (long-term DCA) | Advanced investors with research skill |
| Representative tools | CSI 300 ETF, CSI 500 ETF, S&P 500-linked QDII | Individual stock accounts |
- Conclusion: for the vast majority, index investing is the "win-by-not-losing" starting point; individual stocks are the advanced stage "after your research skill can identify excess returns".
- Even index buying needs the right "ruler": bullish on large caps → CSI 300-linked tools; bullish on small-cap themes → CSI 1000-linked; don't judge everything by the SSE Composite.
The VIX Fear Index
- The VIX (Volatility Index) is compiled by CBOE from S&P 500 option implied volatility, measuring the market's expected 30-day volatility — nicknamed the "fear index".
- How to read it:
- VIX < 15: market calm, complacent; typical of bull markets.
- VIX 20-30: volatility above normal; stay alert.
- VIX > 30 and spiking: panic selling in progress, often a short-term emotional extreme.
- VIX falling from highs: panic exhausted, often accompanying a "market bottom".
- Practical use: the VIX is a "contrarian indicator" — when everyone else is terrified is often the best risk-reward moment; but a VIX spike does not mean the bottom is in — confirm with price structure.
💡 The VIX is a contrarian indicator — others' panic is the best opportunity
The VIX is a "contrarian indicator" — when everyone else is terrified is often the best risk-reward moment. But note: a VIX spike does not mean an immediate bottom; you must confirm the bottom signal with price structure, or you will repeatedly catch knives mid-slope while the panic continues.
- Note: A-shares have no official VIX; domestically people watch the "China VIX" (launched then discontinued; per latest) — panic sentiment can be gauged from option implied volatility, combined market turnover, and the count of limit-up/limit-down stocks.
Risk Warning
⚠️ Risk Warning
- An index does not mean "guaranteed gains": in 2008 the S&P 500 and in 2015 the CSI 300 both suffered halving-level drawdowns — index investing carries large loss risk too.
- Index constituents and weights get rebalanced; past returns do not guarantee the future, and tracking error and fees of index funds affect actual returns.
- Sector and style rotation is at heart a "timing" game; chasing hot sectors in and out is one of the main causes of losses.
- All index compositions, constituent counts, weight caps, and rebalancing dates in this article follow the index companies' latest announcements.
- This article does not constitute investment advice; assess your own risk tolerance before deciding.