BTC Options Insights: Why is March 20th a key turning point for volatility?

Author: Murphy

If an investor buys a large number of call options, the counterparty is usually a market maker. After a market maker sells call options, the Delta of their option portfolio will turn negative. To maintain Delta neutrality, they usually need to buy spot or go long on futures to hedge.

However, in the actual market, what truly influences the price path is often not just Delta, but Gamma.

When a market maker is in a Short Gamma state, the closer the price is to the key strike price, the faster its Delta changes. The more the market maker needs to hedge in the direction of the price (buying when it rises and selling when it falls), thus amplifying price volatility.

This is what we commonly refer to as the "Gamma Magnet effect".

In this cycle, the open interest in BTC options has remained at the $40-50 billion level for an extended period, approaching or even exceeding the influence of some futures exchanges. A large amount of capital is expressing direction through options, making the option structure a significant driver of BTC's short-term price path and exerting a deeper influence on price fluctuations.

• Structure maturing on March 20

Looking at the GEX (gamma exposure) maturing on March 20, there is approximately $180 million of gamma exposure around $74,000, and it is a long gamma structure.

(Figure 1 - BTC Options Gamma Risk Exposure_2026.3.20)

In this environment, market makers' hedging activities typically suppress volatility, making it easier for prices to oscillate around the strike price, which objectively creates resistance around $74,000.

• Structure maturing on March 27

However, after March 20th, by the next major exercise date of March 27th, the option structure had changed significantly.

(Figure 2 - Open interest of options by strike price_2026.3.27)

Looking at the OI (Open Interest) structure, the $75,000 strike price may become the most concentrated area of ​​Calls on the expiry date: there are 9,685 BTC of Call OI (call options), while there are only 2,711 BTC of Puts (put options).

The Call OI is significantly higher than the Put OI, indicating that there is a large amount of capital in the market betting that BTC will rise towards $75,000.

• Who's in control: the buyer or the seller?

Of course, the OI structure alone cannot determine whether the market maker is in a short-gamma state, so we need to further observe the premium flow of the $75,000 call.

(Figure 3 - Cumulative change in the premium of a $75,000 strike price call option)

Data shows that during the two weeks from February 28 to March 14, there was a concentrated buying activity in the market, with the net premium for call options rising rapidly from $5.8 million to $19.8 million, showing a clear acceleration trend (blue curve in the chart), while BTC was still fluctuating between $66,000 and $68,000 at that time.

Based on this, we can conclude that the current BTC rebound is not only driven by spot trading, but also by the influence of the options structure, indicating a market demand for call options to position themselves in advance.

• Changes in Gamma structure

Looking at the GEX maturing on March 27, we can see that there is a Gamma exposure of approximately -$2.56 billion around $75,000, which is a significant Short Gamma structure; this is fundamentally different from the one on March 20, both in terms of scale and nature.

Figure 4 - BTC Options Gamma Risk Exposure (March 27, 2026)

This means that if BTC continues to rise towards $75,000 after March 20th, market makers, in a Short Gamma environment, will need to continuously hedge their Delta by buying spot or futures contracts. This behavior could strengthen the upward momentum and create a typical Gamma Magnet effect.

Meanwhile, the $80,000 level above and the $67,000 level below correspond to a long Gamma exposure of $420 million and $390 million respectively. When the BTC price approaches $80,000, it may face stronger volatility suppression (resistance); when it falls back to the $65,000-$67,000 range, it will also receive some buffer.

However, as we can see from Figure 2, the OI around $67,000 is significantly weaker than at $75,000 and $80,000, indicating that the hedging volume and marginal influence in this area are relatively limited. Therefore, compared to the significant Short Gamma core at $75,000, $67,000 is more like a lower buffer rather than strong support.

In short, after the expiry date on March 20, the BTC options structure will make $75,000 the new focus, shifting from "suppressing volatility" to "amplifying volatility," while creating resistance when moving upwards towards $80,000 and support when moving downwards into the $65,000-$67,000 range.

Especially when liquidity gradually becomes scarce, the driving logic of market price movements also changes, which is something we should pay close attention to in the short term.

Delta refers to how much the option price changes when the price of BTC changes. It determines how much BTC a market maker needs to buy or sell to hedge.

For example, a call with a value of 75,000 and a Delta of 0.4 means that if BTC rises by $1,000, the option price will rise by approximately $400.

Gamma refers to how quickly Delta changes as the price of BTC continues to fluctuate; it determines the strength of market makers' hedging, i.e., how quickly and how often they need to adjust their hedging.