What Is Open Interest in Options Trading?

Open interest in options trading is a critical tool that can be used to determine market sentiment on a particular stock, commodity or other underlying asset.

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There are many key factors investors must consider when it comes to options trading. One of the most important is the open interest of an option. But what is open interest in options trading?

Defined as the number of open call or put option contracts for a particular stock, open interest provides investors with a gauge of market sentiment. Here, we will take a closer look at the nuances of open interest and the impact they can have on investment decisions.

What is open interest in options trading?

Unlike trading volume, which accounts for the total number of contracts bought and sold in a given day, open interest is the number of contracts that are currently in circulation for a particular stock, commodity or any other underlying asset. This can show investors how popular and liquid an asset might be vs using trading volume. 

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More importantly, it shows the number of options contracts that have been opened and not closed, expired or exercised at a specific strike. This can be used as a dynamic measure of investor interest in specific assets, and work as an essential tool for prudent investors. 

How do you use open interest in options trading?

To truly grasp the significance of open interest, we must take a closer look at how it works in options trading.

Why open interest rises: As traders and investors initiate new long positions – or sellers open new short positions – in an amount greater than the number of options contracts closed, expired or exercised at that strike in a given trading day, open interest will rise.  

Why open interest falls: When holders of options – either buyers or sellers – close out more positions than were opened at that strike in a given trading day, open interest will fall.

Generally speaking, increasing open interest means new money is coming into the market, while decreasing open interest represents money moving out of the market.

The true value of open interest becomes evident when exploring its impact on investment strategies.

For instance, high open interest, which is when there are a notable number of contracts open at a specific strike, can serve as a barometer of market sentiment. Specifically, it can indicate widespread interest in an asset. Additionally, while open interest doesn't reveal whether those options were bought or sold, it does mean that speculators are watching that particular price level on the underlying asset. And depending on the number of contracts open, this heightened interest can lead to increased trading activity and potential price swings into expiration.

Another way to use open interest in options trading is to view it as a guide to finding the most liquid, or heavily traded, options. High open interest leads to tighter bid-ask spreads, reducing transaction costs and facilitating smoother trades.

Liquidity is crucial in the world of investing. When options are highly liquid, it means there are plenty of buyers and sellers willing to trade. As a result, bid-ask spreads tighten, making it easier and more cost-effective to enter and exit positions.

FAQs about open interest

Can open interest predict market movements? The short answer is no. While open interest provides invaluable insights into market sentiment, it does not possess predictive capabilities. It is best used in conjunction with other indicators to make well-informed investment decisions.

Does higher open interest always indicate better investment opportunities? Not necessarily. While high open interest signifies market interest, it can also lead to increased competition and narrower profit margins for investors. A balanced evaluation of various indicators is essential. 

Remember, open interest includes option sellers. A high amount of open interest could mean there are larger short positions against the particular option.

How frequently does open interest change? Once per day, before the market opens. Unlike volume, which is updated throughout the day as options contracts change hands between buyers and sellers, open interest figures are only updated after all trades for that specific day are processed. This processing takes place overnight, and the data becomes available the next morning. It provides a comprehensive look at the total number of outstanding option contracts.

The bottom line on open interest 

While open interest isn't viewed as a barometer of price movement, it is a useful indicator of market interest in a particular option. This is key for market participants seeking out highly liquid options to trade or include in their portfolios.

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Jared Hoffmann
Contributing Writer, Kiplinger.com

Jared Hoffmann is a highly respected financial content creator and options expert, holding a journalism degree from San Francisco State University. Formerly a Senior Options and Day Trading Editor and on-air personality at Money Morning, he excels in delivering comprehensive options education, technical analysis, and risk management education to traders.