The BSE Sensex or Bombay Stock Exchange Sensitive Index is a value-weighted index composed of 30 stocks with the base April 1979 = 100. It consists of the 30 largest and most actively traded stocks, representative of various sectors, on the Bombay Stock Exchange. These companies account for around one-fifth of the market capitalization of the BSE.

The base value of the Sensex is 100 on April 1, 1979 and the base year of BSE-SENSEX is 1978-79.

At irregular intervals, the Bombay Stock Exchange (BSE) authorities review and modify its composition to make sure it reflects current market conditions.

The abbreviated form "Sensex" was coined by Deepak Mohoni around 1990 while writing market analysis columns for some of the business newspapers and magazines. It gained popularity over the next year or two.

The index has increased by over ten times from June 1990 to today. Using information from April 1979 onwards, the long-run rate of return on the BSE Sensex can be estimated to be 0.52% per week (continuously compounded) with a standard deviation of 3.67%. This translates to 27% per annum, which translates to roughly 18% per annum after compensating for inflation.[citation needed]

[edit] Sensex Milestones
The Sensex crossed the 1,000 mark on July 25, 1990; the 2,000 mark on January 15, 1992; the 3,000 mark on February 29, 1992; the 4,000 mark on March 30, 1992; the 5,000 mark on October 11, 1999; the 6,000 mark on January 2, 2004; the 7,000 mark on June 21, 2005; the 8,000 mark on September 8, 2005; the 9,000 mark on December 09, 2005; and finally the historic 10,000 mark on February 7, 2006. It created another landmark when it touched 11,000 on March 27, 2006. The Sensex closed at a high of 12,903 on 28 Oct 2006 . To reach from the 11,000 mark to the 12,000 mark only took 19 working days, the shortest time interval for a 1000 points climb in BSE Sensex history, surpassing the just set record of 29 days that it took to reach 11,000 from 10,000.

Here is a timeline on the rise and rise of the Sensex through Indian stock market history.

1000, July 25, 1990 - On July 25, 1990, the Sensex touched the four-digit figure for the first time and closed at 1,001 in the wake of a good monsoon and excellent corporate results.
2000, January 15, 1992 - On January 15, 1992, the Sensex crossed the 2,000-mark and closed at 2,020 followed by the liberal economic policy initiatives undertaken by the then finance minister and current Prime Minister Dr Manmohan Singh.
3000, February 29, 1992 - On February 29, 1992, the Sensex surged past the 3000 mark in the wake of the market-friendly Budget announced by the then Finance Minister, Dr Manmohan Singh.
4000, March 30, 1992 - On March 30, 1992, the Sensex crossed the 4,000-mark and closed at 4,091 on the expectations of a liberal export-import policy. It was then that the Harshad Mehta scam hit the markets and Sensex witnessed unabated selling.
5000, October 11, 1999 - On October 8, 1999, the Sensex crossed the 5,000-mark as the BJP-led coalition won the majority in the 13th Lok Sabha election.
6000, February 11, 2000 - On February 11, 2000, the infotech boom helped the Sensex to cross the 6,000-mark and hit and all time high of 6,006.
7000, June 21, 2005 - On June 20, 2005, the news of the settlement between the Ambani brothers boosted investor sentiments and the scrips of RIL, Reliance Energy, Reliance Capital and IPCL made huge gains. This helped the Sensex crossed 7,000 points for the first time.
8000, September 8, 2005 - On September 8, 2005, the Bombay Stock Exchange's benchmark 30-share index -- the Sensex -- crossed the 8000 level following brisk buying by foreign and domestic funds in early trading.
9000, December 09, 2005 - The Sensex on November 28, 2005 crossed 9000 to touch 9000.32 points during mid-session at the Bombay Stock Exchange on the back of frantic buying spree by foreign institutional investors and well supported by local operators as well as retail investors.
10,000, February 7, 2006 - The Sensex on February 6, 2006 touched 10,003 points during mid-session. The Sensex finally closed above the 10K-mark on February 7, 2006.
11,000, March 27, 2006 - The Sensex on March 21, 2006 crossed 11,000 and touched a life-time peak of 11,001 points during mid-session at the Bombay Stock Exchange for the first time. However, it was on March 27, 2006 that the Sensex first closed at over 11,000 points.
12,000, April 20, 2006 - The Sensex on April 20, 2006 crossed 12,000 and touched a life-time peak of 12,004 points during mid-session at the Bombay Stock Exchange for the first time.
13,000, October 30, 2006 - The Sensex on October 30, 2006 crossed 13,000 and still riding high at the Bombay Stock Exchange for the first time. It took 135 days to reach 13,000 from 12,000. And 124 days to reach 13,000 from 12,500. On 30th October 2006 it touched a peak of 13,039.36 & closed at 13,024.26.
14,000, December 5, 2006 - The Sensex on December 5, 2006 crossed 14,000 and touched a life-time peak of 14028 at 9.58AM(IST) while opening for the day December 5, 2006.
On May 22, 2006, the Sensex plunged by a whopping 1100 points during intra-day trading, leading to the suspension of trading for the first time since May 17, 2004. The volatility of the Sensex had caused investors to lose Rs 6 lakh crore ($131 billion) within seven trading sessions. The Finance Minister of India, P. Chidambaram, made an unscheduled press statement when trading was suspended to assure investors that nothing was wrong with the fundamentals of the economy, and advised retail investors to stay invested. When trading resumed after the reassurances of the Reserve Bank of India and the Securities and Exchange Board of India, the Sensex managed to move up 700 points, still 450 points in the red. This is the largest ever intra-day crash (in points terms) in the history of the Sensex.

The Sensex eventually recovered from the volatility, and on October 16, 2006, the Sensex closed at an all-time high of 12,928.18 with an intra-day high of 12,953.76. This was a result of increased confidence in the economy and reports that India's manufacturing sector grew by 11.1% in August 2006.


[edit] Companies in the Sensex
List of BSE Sensex companies provides the full list of companies that have been part of the BSE Sensex since its inception in 1986 (baselined to 1979).

(as of January 1, 2007) [1]

Code Name Sector Adj. Factor
500410
ACC
Cement
0.65

500490
Bajaj Auto
Automobiles (2/3 wheelers)
0.70

500103
BHEL
Capital Goods
0.35

532454
Bharti Airtel
Telecom and Retail
0.35

500087
Cipla
Pharma
0.65

500124
Dr. Reddy's Laboratories
Pharma
0.75

500300
Grasim Industries
Diversified
0.75

500425
Gujarat Ambuja Cements
Cement
0.80

500010
HDFC
Finance
0.90

500180
HDFC Bank
Finance
0.80

500182
Hero Honda Motors
Automobile (2 wheelers)
0.50

500440
Hindalco Industries
Metal, Metal Products & Mining
0.75

500696
Hindustan Lever Limited
FMCG
0.50

532174
ICICI Bank
Banking & Finance
1.00

500209
Infosys
Information Technology
0.80

500875
ITC Limited
FMCG
0.70

500510
Larsen & Toubro
Capital Goods & Construction.
0.90

532500
Maruti Udyog
Automobiles
0.40

532555
NTPC
Power
0.15

500312
ONGC
Oil & Gas
0.20

500359
Ranbaxy Laboratories
Pharma
0.70

532712
Reliance Communications
Telecom
0.35

500390
Reliance Energy
Power
0.75

500325
Reliance Industries
Diversified
0.55

500376
Satyam Computer Services
Information Technology
0.95

500112
State Bank of India
Banking & Finance
0.45

532540
Tata Consultancy Services
Information Technology
0.20

500570
Tata Motors
Automobiles
0.60

500470
Tata Steel
Metal, Metal Products & Mining
0.70

507685
Wipro
Information Technology
0.20