Positive vs. Negative Gamma: Two Very Different Market Conditions

I only recently discovered that there is a hidden world beneath the surface of the stock market that influences price movements but remains largely unknown to everyday investors and traders. You don't have to be a professional investment banker to understand it. This article has what you need to know.

In the world of the S&P 500 (SPX), professional options dealers (or “market makers”) exert massive influence on how the stock market moves. This influence is captured by a metric called "gamma." Knowing whether the market is in a positive gamma or negative gamma regime tells you how options dealers are most likely to hedge their risk when prices go up or down. For stock traders, this information is just as important as knowing whether you are driving a car with working brakes or stepping on a slippery sheet of ice.

Positive Gamma = Market Stability

When the S&P 500 is in a positive gamma regime, options dealers tend to act as market stabilizers. To hedge their exposure, dealers are generally required to buy stocks when prices decline and sell stocks when prices rise. In other words, dealers hedge against the direction of the market’s movement, which helps dampen volatility and create a more stable trading environment.

A positive gamma environment is typically associated with lower volatility, where stocks tend to grind gradually and steadily higher. Price movements are generally more orderly and contained. In this type of regime, strategies that rely on range-bound trading or selling options premium often perform well because the market tends to be more predictable and volatility remains relatively subdued.

Negative Gamma = Market Volatility

By contrast, a negative gamma regime can turn options dealers into volatility accelerators. In this environment, dealers generally need to sell when prices decline and buy when prices rise. In other words, dealers hedge in the same direction as the market’s movement, which can amplify price swings and push the market further in the direction it is already moving.

Negative gamma is typically associated with higher volatility, characterized by sharp declines and equally rapid, explosive snapbacks. Intraday price ranges can become wide and erratic. When bad news hits, a sell-off can quickly snowball into a larger decline as dealers sell shares to hedge their exposure. Conversely, rallies can develop into rapid upward squeezes as dealers are forced to buy into rising prices. In this environment, short-term momentum and trend-following strategies tend to perform better, while option sellers can face significantly greater risk.

How to Know if SPX Gamma is Positive or Negative

There are free gamma exposure (GEX) tools online. I use:

https://www.insiderfinance.io/gamma-exposure/SPX

This link takes you to a page with the information shown below. If the Net GEX amount is green, then SPX is in a positive gamma regime.  If the Net GEX amount is red, then SPX is in a negative gamma regime.

For now, don’t worry about options terminology like calls or puts, or the fancy strike histogram you will also see on this page. Just focus on whether or not the general market (SPX) is in positive or negative gamma so you can predict how price movement is likely to behave on a given day.

Trading Implications

For a beginner, identifying the S&P 500’s gamma regime can help you align your trading style with the market’s underlying mechanics:

• When gamma is positive, expect a relatively calm market that drifts upward. Volatility tends to be lower, patience is rewarded, and buying dips can be advantageous.
• When gamma is negative, buckle up for a wild ride. Protecting capital, reducing position sizes, and being prepared for rapid price movements in either direction become essential for survival.

This is a key lesson I’ve learned from one of my mentors, a former market maker who spent more than 20 years working at major futures and metals exchanges in London. His advice has been simple:

Do most of your buying when the market is in positive gamma, and when gamma turns negative, focus less on making money and more on reducing risk.

In a negative gamma environment, preserving capital and avoiding unnecessary exposure can be more important than chasing opportunities.