---
title: "Get Skew Delta Signal"
method: GET
path: "/api/signals/basic/skew-delta"
tags: ["Trade Signals"]
---

# Get Skew Delta Signal

`GET /api/signals/basic/skew-delta`

## 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/basic/skew-delta`
- Auth: HTTP bearer

Short-dated OTM put-vs-call IV deviation — real-time fear gauge.

Answers: *are traders paying an unusual premium for downside protection
right now?* Equity-index skew is structurally positive (OTM puts always
trade richer than OTM calls), so this signal scores the **deviation
from normal**, not the raw spread. Bid-up put skew typically moves
*before* the tape confirms bearishness — useful leading-indicator.

**Logic highlights** (`src/signals/basic/skew_delta.py`):
- `spread = otm_put_iv − otm_call_iv` from `ctx.extra['skew']`
  (populated by the unified engine from `option_chains` near ATM).
- `deviation = spread − SIGNAL_SKEW_BASELINE` (default baseline 0.02).
- `score = −clip(deviation / SIGNAL_SKEW_SATURATION, [-1, 1])`
  (default saturation 0.04). Negative sign: elevated put skew → bearish.
- **Abstains (score=0)** if `otm_put_iv` or `otm_call_iv` is missing.

**Params:**
- `symbol` (default `SPY`). Returns 404 if no row exists yet.

**Returns:**
```json
{
  "underlying": "SPY", "timestamp": "...",
  "clamped_score": -0.35, "score": -35.0, "direction": "bearish",
  "weighted_score": 0.0, "weight": 0.0,
  "otm_put_iv": 0.192,
  "otm_call_iv": 0.147,
  "spread": 0.045,
  "deviation": 0.025,
  "context_values": {
    "otm_put_iv": 0.192, "otm_call_iv": 0.147,
    "spread": 0.045, "baseline": 0.02, "deviation": 0.025
  },
  "score_history": [{"score": -14.1, "timestamp": "..."}, "...up to 90"]
}
```

- `score` / `clamped_score` — `[-100, +100]` / `[-1, +1]`; negative = fear bid.
- `otm_put_iv` / `otm_call_iv` — IV as a fraction (e.g. `0.18` = 18%). `null` if missing.
- `spread` — `otm_put_iv − otm_call_iv`; typically `[0, 0.10]` for SPY. `null` if missing.
- `deviation` — `spread − baseline`; sign drives the score (positive → bearish score).
- `context_values` — the above plus `baseline` (the neutral-skew reference).
- `score_history` — up to 90 recent points.

**Trader interpretation.**
- `score < −40` → meaningful fear bid; tighten longs, consider downside hedges.
- `score > +30` (rare, call skew) → potential upside squeeze / short-covering setup.
- Steady negative drift while price rallies → distribution / bull-trap warning.
- `otm_put_iv == null` → no short-dated data this cycle; not the same as neutral.

**Page design.** Bidirectional ±100 gauge labeled "fear" (left) / "euphoria"
(right). Below, a two-line mini-chart of `otm_put_iv` and `otm_call_iv` as
% IV over `score_history` length, with a horizontal reference line at
`baseline` (the "normal skew" line). Color the gauge card red when
`score ≤ -40`, green when `score ≥ +30`.

## 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)