Hedging through Futures: Hedging means protecting one's portfolio from impact of market changes. This amounts to giving up or shedding risk.
Any asset (including an equity share) is subject to two kinds of risk: one is called Specific Risk that relates to its inherent risk and the other is Systematic Risk or Market Risk. If you own Tata Steel share, consequences of Tata Steel management's business style is the specific risk. Consequences arising from factors which affect all companies and not Tata Steel alone form the Market Risk or Systematic Risk.
If you want to give up specific risk without selling the share, you will have to 'diversify' your holdings (portfolio) so that you are less affected by factors that impact Tata Steel exclusively. If diversification is random and large enough, you may completely shed the specific risk of owning Tata Steel share.
But, diversification does not reduce market risk. One indicator of market risk in the equity market is what happens to a particular share's price when the index (say Nifty) moves up or down. This indicator or relationship is called 'beta'. Beta of a share is 1 if there is the same percentage change in the price of share as the change in index, say Nifty. If Nifty increases by 5% and the share's price also increases by 5%, we say that the beta of this share is 1. If the price of share goes up by 10%, it means beta is 2.
Nifty index can be bought and sold in the market. Suppose the Nifty index is now Rs.8,000. If Nifty moves up by 5%, Nifty index will be worth Rs.8,400. If you had shares worth Rs.4,000 when Nifty index was Rs.8,000 and beta of your shares is 2, your shares will be worth Rs.4,400 after Nifty has increased by 5%. This means that the increase in the value of your shares is the same as increase in the price of Nifty index.
Concept of 'beta' is made use of to hedge against market risk. In the example given above, if you sell one Nifty index in the Futures market (i.e. short one Nifty index futures), what you gain from owning shares would be offset by what you lose in the Nifty Futures sold. Similarly, if you lose from your share holdings, you will gain the same amount from the Nifty Futures sold. This is an example of 'perfect hedge'. Depending on your capacity and willingness to absorb market risk, you may opt for partial hedges.
When you own a collection (portfolio) of shares of different companies, beta of the portfolio is the weighted average beta of all shares, the weights being the market values of shares.
'Hedge Ratio' means the number of Nifty indices you need to short in order to neutralise or shed market risk totally. This is equal to Market value of portfolio multiplied by beta of portfolio and divided by value of Nifty index. (Note: Nifty index is taken as an example. Similarly, you can consider Sensex as an index or midcap index or any other index. It should however be noted that beta of a share will be different depending on the index. In addition, beta changes over time.)