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What You’ll Learn

How to read the Open Interest page, what the strike bubbles mean, and how to use put-call ratio, max pain, call wall, and put wall alongside GEX and options-chain views.

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What Open Interest Shows

Open Interest is the outstanding options positioning snapshot for SPY and SPX. It is slower-moving than intraday flow: it tells you where contracts remain open by strike and expiry, not what traded during the current minute. Hermes shows:
  • call and put open interest by strike
  • selectable expiries, with 0DTE highlighted when available
  • a strike-range slider for zooming into the relevant area
  • summary levels for put-call ratio, max pain, call wall, and put wall when the selected snapshot includes them
Use it as the structural layer behind the faster tools. Quote Flow shows current NBBO quote clustering. GEX flow charts show intraday gamma being added or removed. Open Interest shows where existing options positioning is already concentrated.

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Reading The Chart

The Open Interest chart plots call and put bubbles across strikes. Large bubbles mark strikes with more outstanding contracts. A large call bubble above spot or put bubble below spot can matter because many participants may be watching or hedging around that level.
Open interest is not live trade flow. It updates from the options snapshot and should be treated as positioning context, not a real-time tape read.

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Summary Levels

When available, Hermes shows four summary fields under the chart: The wall levels are most useful when they line up with price behavior, GEX, or Session Pulse levels. A wall that price ignores is just background context.

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How To Use It

1

Pick the symbol

Switch between SPY and SPX depending on the product you are reading.
2

Choose expiries

Start with 0DTE when it is available, then add nearby expiries if you want a broader structural read.
3

Narrow the strike range

Use the slider to focus on the strikes near spot. Wide ranges are useful for context, but near-spot concentration usually matters more intraday.
4

Cross-check the levels

Compare call wall, put wall, max pain, and visible strike bubbles against GEX Combined, the price chart, and Quote Flow.

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Common Misreads

  • Treating open interest as today’s flow: OI is outstanding positioning, not what just traded.
  • Over-weighting max pain: max pain can help frame the day, but price can ignore it when volatility, news, or flow dominate.
  • Ignoring expiry selection: one selected expiry can tell a different story than several expiries combined.
  • Reading a wall alone: a call or put wall is stronger context when GEX, price, and Session Pulse are pointing at the same area.