Learn about S&P 500, Dow Jones, NASDAQ Composite

1.2.11 · Stock-Market › Shares, Ownership & Indices

Overview

Stock market indices measurement tools hain jo ek specific group of stocks ki performance track karte hain, taaki hume ek single number mile jo bataye "market kaisi chal rahi hai." Inhe market health ke thermometers ki tarah socho—temperature ki jagah ye selected companies ki collective value measure karte hain.

Har index alag selection criteria (kaun se stocks include karne hain) aur calculation methods (unki prices ko ek number mein kaise combine karna hai) use karta hai. Teen giants—S&P 500, Dow Jones, aur NASDAQ Composite—har ek market ke baare mein alag story batata hai.

The S&P 500 (Standard & Poor's 500)

Yeh Kya Measure Karta Hai

S&P 500 approximately total US stock market value ka 80% represent karta hai. Isme sabhi 11 major sectors (Technology, Healthcare, Financials, Consumer Discretionary, etc.) ki companies shaamil hain.

Selection Criteria:

US company honi chahiye
Market cap ≥ $14.5 billion (2026 ke hisaab se)
Adequate liquidity (average trading volume)
Kam se kam 50% shares public ke liye available (free float)
Sabse recent quarter mein positive earnings AUR pichle 4 quarters ka sum bhi positive

Yeh Calculate Kaise Hota Hai

$Index Level = \frac{\sum _{i = 1}^{500} P _{i} \times Q _{i}}{D} \times B$

Jahan:

$P_{i}$ = Stock $i$ ki price
$Q_{i}$ = Stock $i$ ke liye outstanding shares ki sankhya (free float ke liye adjust ki gayi)
$D$ = Divisor (corporate actions ke liye adjust hone wala proprietary number)
$B$ = Base value (typically set kiya jaata hai taaki index ek round number se shuru ho)

Market-cap weighted kyun? Apple (market cap $3 t r i l l i o n) m e in$ 1 ka change index ko ZYADA impact karna chahiye compared to ek chhoti company (market cap $15 bi l l i o n) m e in$ 1 ke change se. Yeh weighting economic reality reflect karti hai—badi companies ka zyada influence hota hai.

First Principles Se Derivation:

Goal: 500 companies ki total value represent karne wala ek single number banana
Total Market Value: $Total = \sum_{i = 1}^{500} (Price_{i} \times Shares_{i})$
Problem: Yeh number bahut bada hoga (trillions mein). Hume kuch human-readable chahiye.
Solution: Ise ek constant (divisor $D$ ) se divide karo taaki scale down ho jaye
Problem #2: Corporate actions (stock splits, dividends) artificially is number ko change karte hain
Solution: Jab bhi koi corporate action ho, divisor $D$ ko adjust karo taaki continuity bani rahe

Example: Divisor adjustment kaise kaam karta hai

Maano index 5,000 par hai aur total market cap $40 trillion hai: $5000 = \frac{40 , 000 , 000 , 000 , 000}{D} ⟹ D = 8, 000, 000$

Company X (500 ka hissa) 2-for-1 stock split karta hai. Uski price half ho jaati hai, shares double ho jaate hain, lekin economic value unchanged rehti hai. Phir bhi, formula ab yeh dega: $New calc = \frac{39 , 999 , 900 , 000}{8 , 000 , 000} = 4, 999.99...$

Index gir gaya! Lekin economically kuch bhi nahi badla. Toh hum divisor adjust karte hain: $5000 = \frac{39 , 999 , 999 , 900 , 000}{D _{new}} ⟹ D_{new} = 7, 999, 999, 980$

Yeh split ke bawajood index ko 5,000 par rakhta hai.

Step 1: Index mein Apple ka weight calculate karo $w_{Apple} = \frac{3 , 000 , 000 , 000 , 000}{40 , 000 , 000 , 000} = 0.075 = 7.5%$

Yeh step kyun? Market-cap weighting ka matlab hai ki har company apne size ke proportion mein contribute karti hai.

Step 2: Index movement mein contribution calculate karo $Δ Index = w_{Apple} \times Δ P_{Apple} = 0.075 \times 2% = 0.15%$

Yeh step kyun? Ek company ke price change ko uske weight se multiply karne par uska isolated impact milta hai.

Answer: S&P 500 sirf Apple ki movement se approximately 0.15% badhega.

The Dow Jones Industrial Average (DJIA)

Yeh Kya Measure Karta Hai

Dow US ki 30 sabse significant companies represent karta hai, jinhe Wall Street Journal ke editors haath se chunte hain. Examples: Apple, Microsoft, Boeing, Coca-Cola, Goldman Sachs.

S&P 500 Se Key Difference: Sirf 30 stocks (vs 500), aur market cap ki jagah stock price se weighted.

Yeh Calculate Kaise Hota Hai

Jahan:

$P_{i}$ = Stock $i$ ki price
$D_{Dow}$ = Dow Divisor (splits/changes ke liye adjust hota hai, currently ~0.152 as of 2026)

Price-weighted kyun? Historical accident. Jab Charles Dow ne ise 1896 mein create kiya, 30 companies ka market cap calculate karna computationally mushkil tha. Prices add karna simple tha.

Derivation:

Original 1896 method: Simply prices ka average nikalo $Average = \frac{P _{1} + P _{2} + ... + P _{30}}{30}$
Problem: Jab ek stock split hota hai (maano, 2-for-1), uski price half ho jaati hai, jisse average gir jaata hai, halanki koi value lost nahi hui
Solution: Denominator (30) ko ek adjustable divisor $D$ se replace karo $DJIA = \frac{\sum P _{i}}{D}$
Maintenance: Jab corporate actions hoon, $D$ ko adjust karo taaki index continuous rahe (S&P 500 jaisa hi principle)

Agar dono $3 badhti hain (A ke liye 1% move, B ke liye 10% move), toh Dow par kya impact hoga?

A ka Impact: $\frac{3}{D}$
B ka Impact: $\frac{3}{D}$

Same impact! Halanki Company B economically 4× badi hai aur percentage terms mein 10× zyada move ki.

Yeh step kyun matter karta hai: Yahi DJIA ki quirk reveal karta hai—company size ki parwah kiye bagair ek high-priced stock ka zyada influence hota hai. UnitedHealth (stock price ~ $500) D o w k o A ppl e (s t oc k p r i ce$ 190) se zyada move karta hai, halanki Apple kahin zyada valuable hai.

Steel-man argument: Historical comparisons ke liye tradition aur continuity ki value hoti hai.

Yeh misleading kyun hai:

Sirf 30 companies (vs S&P ke 500) = bahut kam representative
Price-weighting economically arbitrary hai—ek stock split influence badal deta hai
S&P 500 woh index hai jo professionals benchmarking ke liye actually use karte hain

Fix: Dow ko historical context aur headline sentiment ke liye use karo, lekin actual market measurement ke liye S&P 500 par rely karo.

NASDAQ Composite

Yeh Kya Measure Karta Hai

NASDAQ Composite tech-heavy hai kyunki NASDAQ exchange historically technology aur growth companies ko attract karta raha hai (Microsoft, Apple, Amazon, Google, Tesla, NVIDIA sab yahan list hain). Yeh approximately 3,000-3,500 companies represent karta hai, halanki market-cap weighting ki wajah se top 10 companies index ka ~45% banati hain.

Selection Criteria:

NASDAQ exchange par listed hona chahiye
Common stocks, REITs, ADRs included
Koi aur criteria nahi—agar tum NASDAQ par ho, tum index mein ho

Yeh Calculate Kaise Hota Hai

Jahan $N$ ≈ 3,000+ (sabhi NASDAQ-listed stocks). Calculation method S&P 500 ke identical hai (market-cap weighted), lekin universe "is exchange par sab kuch" hai, na ki "selected large companies."

Sabhi stocks kyun include karte hain? NASDAQ apne exchange ki performance ka comprehensive measure chahta tha. S&P 500 aur Dow cherry-pick karte hain; NASDAQ Composite all-inclusive hai.

Interpretation:

Broad market (S&P 500) moderately badha
Blue-chip industrials (Dow) slower badhe—older economy companies peeche rahi
Tech-heavy stocks (NASDAQ) surge kiya—growth/tech sector ka strong day raha

Yeh kyun matter karta hai: Alag indices alag stories batate hain. Ek "market rally" actually ek "tech rally" ho sakti hai agar NASDAQ S&P 500 se kaafi zyada aage nikal jaaye.

Teeno Indices Ki Comparison

Feature	S&P 500	Dow Jones	NASDAQ Composite
Number of Stocks	500	30	~3,000+
Weighting Method	Market-cap	Price	Market-cap
Coverage	Large US companies	30 blue-chips	All NASDAQ stocks
Sector Bias	11 sectors mein balanced	Thoda industrial tilt	Heavy tech (45%+)
Creation Year	1957	1896	1971
Use Case	Professional benchmark	Media headline	Tech sector proxy

Investors Ke Liye Indices Kyun Matter Karte Hain

1. Performance Benchmarking

Agar tumhare portfolio ne pichle saal +12% return diya lekin S&P 500 ne +18% diya, toh tumne market se underperform kiya. Indices comparison baseline provide karte hain.

2. Passive Investing

Index funds aur ETFs (Exchange-Traded Funds) indices ko replicate karte hain. Jab tum S&P 500 index fund khareedte ho, tum automatically sabhi 500 companies ka ek tiny slice own karte ho.

Index funds ka math:

Kyun? Fund index ke exact weights mein stocks khareedata hai, isliye yeh index ke saath move karta hai (management fees minus, typically 0.03-0.20% annually).

3. Market Sentiment Indicator

Badhta S&P 500 investor confidence suggest karta hai; girna darr suggest karta hai. Indices hazaron investment decisions ko ek signal mein aggregate karte hain.

Common Misconceptions

Yeh galat kyun hai: Index levels dimensionless ratios hain. Dow at 40,000 ka matlab hai ki current value 1896 ki (adjusted) base value ki 40,000× hai. Yeh dollars, shares, ya companies nahi hain—yeh ek pure comparison number hai.

Fix: Indices ko thermometers ki tarah socho: 98.6°F ka matlab "98.6 cheezein" nahi hota, yeh ek scale-based measurement hai.

Yeh partially galat kyun hai: NASDAQ Composite mein retail (Costco), healthcare (Gilead), aur