sensex

The Sensex is an indicator of the performance of 30 companies spanning various sectors, which are representative of the economy as a whole. The basic premise being that if the 30 best compnaies in the country do well then the economy is also doing well.

How are the daily numbers calculated? The sensex uses something called as the free-float market capitalisation.

Mathematically free-float capitalization for a stock is represented as,

Free-float factor X market capitalization

Consider a company called xyz, it’s free float factor value is 0.6 and it has the market capitalization of Rs.50000, then free-float capitalization is calculated as 0.6 x 50,000 = Rs.30, 000.

Steps to calculate sensex

• Free- float market capitalization of each company is calculated
• Add all the above results to obtain total free-float market capitalization value
• Apply relative weight method

To understand the third step,  Consider the total free-float market capitalization at a point of time is Rs.5000000, Say at that instant sensex is 3000… After a year or so, total free-float market capitalization has raised to Rs.6000000 then the new sensex will be???

Total market capitalization ——————sensex
Rs.5000000 ————————————-3000——- (say at time ‘Z’)
Rs.6000000 —————————————? ——— (say some times after ‘Z’)

Here we have to apply ratio and proportion concept,

i.e. 5000000 / 6000000 = 3000 /?

? = 3000 x (6/5) = 3600

Now 3600 is the new sensex point…

Same calculation holds good for nifty index too… For sensex we calculate total free-float market capitalization of 30 stocks and for nifty index we calculate for 50 stocks…

[One more question that will arise soon is that what is the starting point considered to make this relative calculation!!! Answer for this is the base year... for sensex 1978-1979 is assumed to be the base year, at that point sensex base is assumed be 100 and for Nifty index ,3rd NOV 1995 is assumed to be the base year with base value of 1000 ...]

Note: All these sensex & Nifty index calculations are carried out in real time and are refreshed out at a regular interval of every 15 sec…. anyway if confused just keep this in mind if the sensex or nifty index goes up, the market is doing well or else it’s not.

Market capitalization adjustment:

Suppose if a company gives bonus for its share holders then new sensex will be based on some adjustment in the total market capitalization….

Total market capitalization (new) = Total market capitalization (old) x [New market capitalization of stock / old market capitalization of stock]

Rest calculation remains same…