---
title: "Get Vol Expansion Signal"
method: GET
path: "/api/signals/advanced/vol-expansion"
tags: ["Trade Signals"]
---

# Get Vol Expansion Signal

`GET /api/signals/advanced/vol-expansion`

## Request

- Base URL: `https://api.zerogex.io` (the document declares no server; this is the origin it was published from)
- URL: `https://api.zerogex.io/api/signals/advanced/vol-expansion`
- Auth: HTTP bearer

Volatility expansion forecast — expansion readiness + directional bias.

Answers two questions at once: *Will vol expand?* (GEX-driven) and
*If it does, which way?* (momentum-driven).

**Logic highlights** (`src/signals/advanced/vol_expansion.py`):
- `expansion = gex_readiness × 100` (0–100); short-gamma regimes raise readiness.
- `direction_score = tanh(momentum_z / 1.0) × 100` based on a 5-bar z-score.
- `score = (expansion × direction_score) / 100` — sign matches direction,
  magnitude gated by expansion readiness.

**Params:** `symbol` (default `SPY`). Returns 404 when no data exists.

**Returns:**
```json
{
  "underlying": "SPY", "timestamp": "...",
  "clamped_score": 0.42, "weighted_score": 0.084, "weight": 0.20,
  "direction": "bullish",
  "score": 42.0,
  "expansion": 78.4,
  "direction_score": 53.5,
  "magnitude": 41.9,
  "expected_5min_move_bps": 14.2,
  "context_values": { "...full engine context..." },
  "score_history": [{"score": 42.0, "timestamp": "..."}, "...up to 90"]
}
```

- `score` — [-100, +100]; product of expansion × direction, scaled.
- `expansion` — [0, 100]; GEX-driven vol-expansion readiness.
- `direction_score` — [-100, +100]; momentum-driven directional bias.
- `magnitude` — [0, 100]; absolute size of the combined signal.
- `expected_5min_move_bps` — forecasted 5-minute move in basis points.
- `direction` — `"bullish"` | `"bearish"` | `"neutral"`.
- `score_history` — up to 90 recent `{score, timestamp}` points, newest→oldest.

**Trader interpretation:**
- `expansion > 60` + `|direction_score| > 50` → high-conviction expansion;
  long gamma or directional debit spread in the direction sign.
- `expansion < 30` → wait; dealers long gamma, likely pinning.
- Direction-score sign-flip while expansion stays high → whipsaw warning.

**Page design.** Two half-circle gauges (expansion + direction_score), a
"expected 5-min move" number (bps), and a sparkline of `score_history`.
Color the card green/red by direction when `|score| ≥ 25`.

## Query parameters

- `symbol` string

## Response `200`

Successful Response

- unknown

## Other responses

- `422`: Validation Error

---

[API](https://skmtc.dev/zerogex/apis/zerogex-api.md) · [All operations](https://skmtc.dev/zerogex/apis/zerogex-api/llms.txt) · [OpenAPI document](https://skmtc.dev/zerogex/apis/zerogex-api/revisions/753b26bf0592?raw)