The put to call ratio (PCR) is a mathematical indicator that investors use to determine market sentiment. The ratio reflects the volume of put options and call options placed on a particular market index. Analysts interpret this information into either a bullish (positive) or bearish (negative) near-term market outlook.
The idea is simple: the ratio of how many people are betting against the market versus how many people are betting in favor of the market, should provide a gauge of the general mood investors are in.
A high put-call ratio is thought to be bearish (because more investors are taking short positions) while a low put-call ratio is thought to be bullish (because more investors are taking long positions). Investor Martin Zweig invented the put-call ratio and used it to forecast the 1987 stock market crash.
What are Puts and Calls?
Puts and calls are the most basic types of options contracts. Options contracts give holders the right, but not the obligation, to buy or sell a specific number of shares of a given security by a certain date (the expiration date) at an agreed upon price (the strike price). For both puts and calls, one options contract is usually for 100 shares of the underlying security.
The seller of an option is also sometimes called the writer. Options writers receive a fee, called a premium, in exchange for the risk of having to buy or sell shares when the holder of the option chooses to exercise their contract.
There are many factors that influence an option’s premium, and many ways to calculate the value and the risk of options, including the Black-Sholes, trinomial, and Monte Carlo simulations.
Those interested in trading calls and puts and other options strategies may want to research the details further with our options trading guide.
For now, we’re concerned with the basics of call vs. put options so we can better understand the put-call ratio and what it means.
Puts
A put option (or “put”) gives its owner the right to sell a certain number of shares at a predetermined price by a certain date. Investors may also refer to puts as “short positions” because they represent bearish bets on a security’s future.
An investor who buys a put has the option to sell the stock at some point leading up to the expiration date of the contract. Investors may use puts in a variety of ways within the portfolio. For example, a protective put allows an investor who already owns the underlying asset to benefit even if the price of that stock asset goes down.
Calls
A call gives its owner the right to buy a certain number of shares at a predetermined price by a certain date. Calls are also referred to as long positions because they represent bullish bets on a security’s future.
An investor who buys a call has the option to buy the stock at some point leading up to the expiration date.
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What Is Put Call Ratio?
The put-call ratio is a measurement of the number of puts versus the number of calls traded on a given security over a certain timeframe. The ratio is expressed as a simple numerical value.
The higher the number, the more puts there are on a security, which shows that investors are betting in favor of future price declines. The lower the number, the more calls there are on a security, indicating that investors are betting in favor of future price increases.
Analysts most often apply this metric to broad market indexes to get a feel for overall market sentiment in conjunction with other data point. For example, the Chicago Board Options Exchange put-to-call ratio is one of seven factors used to calculate the Fear & Greed Index by CNN Business.
The put-call ratio can also be applied to individual stocks by looking at the volume of puts and calls on a stock over a certain period.
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How to Calculate the Put-Call Ratio
The put-call ratio equals the total volume of puts for a given time period on a certain market index or security divided by the total volume of calls for the same time period on that same index or security. The CBOE put call ratio is this calculation for all options traded on that exchange.
There can also be variations of this. For example, total put open interest could be divided by total call open interest. This would provide a ratio for the number of outstanding puts versus the number of outstanding calls. Another variation is a weighted put-call ratio, which calculates the dollar value of puts versus calls, rather than the number.
Looking at a put call ratio chart can show you how that ratio has changed over time.
Put-Call Ratio Example
Suppose an investor is trying to assess the overall sentiment for a stock. The stock showed the following volume of puts and calls on a recent trading day:
Number of puts = 1,400
Number of calls = 1,800
The put call ratio for this stock would be 1,400 / 1,800 = 0.77.
How to Interpret the Put-Call Ratio
A specific PCR value can broadly be defined as follows:
• A PCR of less than 1 implies that investors are expecting upward price movement, as they’re buying more call options than put options.
• A PCR of more than 1 implies that investors are expecting downward price movement, as they’re buying more put options than call options.
• A PCR equal to 1 indicates investors expect a neutral trend, as purchases of both types of options are at the same level.
However, while PCR has a specific, mathematical root, it is still open to interpretation, depending on your options trading strategy. Different investors might take the same value to have different meanings.
Contrarian investors, for example, typically believe that the majority is wrong. The best move is to act contrary to what others are doing, in this view. If everyone else is buying something, contrarians believe it might be a good time to sell, or vice-versa. A contrarian investor might therefore perceive a high put/call ratio to be bullish because it suggests that most people believe prices will be heading downward soon.
Momentum investors believe in trying to capitalize on prevailing market trends. “The trend is your friend,” they might say. If the price of something is going up, it could be best to capitalize on that momentum by buying, in this view. A momentum investor could believe the opposite, and that a high PCR should be seen as bearish because prices could be trending downward soon.
To take things a step further, a momentum investor might short a security with a high put-call ratio, hoping that since most investors appear to already be short, this will be the right move. On the other hand, a contrarian investor could do the opposite and establish a long position, based on the idea that what most people expect to happen is the opposite of what’s actually coming.
The Takeaway
The put-call ratio is a simple metric used to gauge market sentiment. While often used on broad market indexes, investors may also apply the PCR to specific securities. Calculating it only involves dividing the volume of puts by the volume of calls on the market for a security.
The put-call ratio is one factor you might consider as you start trading options. A platform like SoFi’s allows you to get started with options trading, thanks to its intuitive and user-friendly design. Investors can also reference a library of educational resources about options.
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