Open Interest-The big O of F&O
Open Interest-The big O of F&O

Chapter 6

Open Interest-The big O of F&O

Options on NSE, like Nifty options or equity options also possess open interest at different strike prices. The accounting of open interest in options is the number of open positions or unsettled positions of a particular option instrument of a specific strike price, with a pre-determined expiry.

Option writing refers to selling of the option contract, writers are the one who bring options into existence by selling them. Just like Insurance contracts come into existence by Insurance companies selling them. 

The Market views differ but unlike Option Buyers Not only one of the two (Up or Down) directions, But also No move helps option writer.  


While Call Buyers' Bias = Bullish 

Call Writers' Bias  = Neutral to Bearish 




While Put Buyers' Bias = Bearish 

Put Writers' Bias  = Neutral to Bullish


This brings us to an interesting inference 


Call Writers' Expectation = Stock/Index =< Strike Price or Stock/ Index Rise could be Capped at Strike Price 


Put Writers' Expectation = Stock/Index => Strike Price or Stock/ Index Fall could be Floored at Strike Price 


On the other hand, Call Undwinding / Put Unwinding could also be seen as lowering Writers' Interest a.k.a. confidence in aforementioned Capped or Floored Strike Price


Call Unwinding (especially where OI is highest) = Expectation of Higher Cap or More room to Rise


Put Unwinding (especially where OI is highest) = Expectation of even lower Floor or More room for Fall 

This can be conveniently observed in the OPEN INTEREST tool of Quantsapp, where the red bars indicate open interest of Nifty put options and green bars indicate the open interest of Nifty call options, as indicated in the template ahead.

The business of risk is essentially an agreement between risk takers (insurance companies) and risk averse (insurance policy holder).

Similarly, the open interest study can be carried out for different F&O stocks in India and also listed equity indices, all through Quantsapp.


For every open interest, there is a buyer and there is a seller of the financial instrument under consideration; in our case, NSE F&O options.

But the open interest data is studied from option writers’ perspective, because they are the traders/participants with deep pockets, as writing entails assuming theoretically unlimited risk and limited reward (restricted to option premium). Also, it requires the participant to put up initial margin with the exchanges. With lot at stake, there is a perspective in the market, that these option writers or option sellers may have a better inkling/hint as to where the underlying is headed.

For example, in the insurance business, the insurance company undertakes underwriting of policies and determines the terms of conditions of the insurance policy based on their guesstimates of probable returns to risks inherent in the particular transaction for which the policy has been underwritten. While, consumers are large in numbers but the transaction tends to be skewed in favour of the insurance company, rather than the insurance purchaser (consumer). This is similar to the case of option writer or option seller and option buyer.

The business of risk is essentially an agreement between risk takers (insurance companies) and risk averse (insurance policy holder).

Takeaway:  Risk Takers make Business of Risk Possible


How is open interest of options defined?

Open interest in case of options is strike-wise. It is the number of unsettled contracts of a particular option type, with a specific strike price for a specific underlying.

How can open interest in options be monitored?

NSE F&O segment stocks and indices like Nifty, Bank nifty can easily be monitored live using the Quantsapp open interest tool.

Where can I get open interest data on Nifty options?

Nifty, Bank Nifty and other F&O stocks’ option open interest can be followed on a live basis with effective colour coding used for calls and puts across strike prices and sound demarcation of option open interest addition and unwinding.

Is Option open interest data is studied from the option sellers’ perspective?

Yes, as option seller has more at stake in the market, with possibility of unlimited losses and receiving only option premium. This is similar to an insurance company issuing policies to consumers.