Buy/Sell Pressure: Live Options Order Flow

This article assumes you already know Net GEX and the Call Wall / Put Wall levels from this guide: here we add the piece that moves in real time on top of those levels.

What Buy/Sell Pressure measures

Gamma levels (Call Wall, Put Wall, Long-Wall, Short-Fuel) describe where the market is positioned at a given moment. Buy/Sell Pressure describes who's aggressing the price right now: it classifies every option trade by whether the buyer paid the ask price or the seller accepted the bid price.

Key idea: an option bought at the ask means someone paid to get in now, without waiting for a better price: that's buyer aggression. An option sold at the bid is seller aggression. Buy/Sell Pressure accumulates that classification strike by strike, live.

How it accumulates

$$ P_{net} = \sum_{i=1}^{n} (V_{ask,i} - V_{bid,i}) $$

Where:

• $P_{net}$ = accumulated net pressure for a contract or group of strikes.
• $V_{ask,i}$ = volume of trade $i$ executed at the ask (buyer aggression).
• $V_{bid,i}$ = volume of trade $i$ executed at the bid (seller aggression).
• $n$ = number of trades accumulated in the observed time window.

A positive $P_{net}$ means buyer aggression dominates that contract or group; a negative value means seller aggression dominates.

How to read direction by option type

Directional interpretation depends on the sign of $P_{net}$ and on whether the aggression happens on Calls or on Puts.

Note: a Put bought at the ask can be a bearish bet or a hedge against a long position in the underlying. Buy/Sell Pressure shows aggression: that's why it's read together with the rest of the levels in this guide.

flowchart TD
    A["Option trade executed"] --> B{"What price did it fill at?"}
    B -->|"At the ask"| C["Buyer aggression"]
    B -->|"At the bid"| D["Seller aggression"]
    C --> E["Accumulates into Buy/Sell Pressure"]
    D --> E
    E --> F["Read by strike and by type (Call/Put)"]

Numeric example

Example: during a session, options on the underlying print 12,000 Call contracts bought at the ask and 7,000 sold at the bid, along with 5,000 Put contracts bought at the ask and 9,000 sold at the bid.

$$P_{net,\ Calls} = 12{,}000 - 7{,}000 = 5{,}000$$ $$P_{net,\ Puts} = 5{,}000 - 9{,}000 = -4{,}000$$

Net buyer pressure on Calls and net seller pressure on Puts (more Puts sold at the bid than bought at the ask). Both reads point the same direction: aggregate bullish bias in that session's flow. Illustrative figures to explain the calculation mechanics.

Next step

You now know how live buyer and seller aggression is measured. The next article connects that pressure with the exact moment the market transitions from one regime to another: Regime Shifting.

Continue with: Regime Shifting: Signal of a Market Regime Change