---
title: "Get Tape Flow Bias Signal"
method: GET
path: "/api/signals/basic/tape-flow-bias"
tags: ["Trade Signals"]
---

# Get Tape Flow Bias Signal

`GET /api/signals/basic/tape-flow-bias`

## 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/tape-flow-bias`
- Auth: HTTP bearer

Signed option-tape premium imbalance — continuous order-flow bias.

Answers: *right now, is the tape aggressively buying calls and selling
puts (bullish) or the reverse (bearish)?* The ingestion layer
Lee-Ready-classifies every print into `buy_premium` / `sell_premium`;
this signal nets them and scores the per-side imbalance. Unlike
`smart_money` (discrete "large premium" events), this watches the
continuous tape — gives an earlier read on directional conviction.

**Logic highlights** (`src/signals/basic/tape_flow_bias.py`):
- `call_net = call_buy_premium − call_sell_premium` (aggressor side).
- `put_net  = put_buy_premium  − put_sell_premium`.
- `directional = call_net − put_net` (call buying = bullish; put buying = bearish).
- `ratio = directional / (|call_net| + |put_net|)` in `[-1, +1]`.
- `score = clip(ratio / SIGNAL_TAPE_FLOW_SATURATION, [-1, 1])` (default saturation 0.6).
- **Abstains (score=0)** if `|call_net| + |put_net| < SIGNAL_TAPE_FLOW_MIN_PREMIUM`
  (default $250K). Treat abstention as "no data," not neutral conviction.

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

**Returns:**
```json
{
  "underlying": "SPY",
  "timestamp": "2026-04-22T18:55:00Z",
  "clamped_score": 0.28, "score": 28.0, "direction": "bullish",
  "weighted_score": 0.0, "weight": 0.0,
  "call_net_premium": 312000.0,
  "put_net_premium": -85000.0,
  "source": "flow_by_type",
  "context_values": {
    "call_net_premium": 312000.0, "put_net_premium": -85000.0,
    "call_buy_premium": 450000.0, "call_sell_premium": 138000.0,
    "put_buy_premium": 120000.0, "put_sell_premium": 205000.0,
    "source": "flow_by_type"
  },
  "score_history": [{"score": 12.4, "timestamp": "..."}, "...up to 90"]
}
```

- `score` / `clamped_score` — `[-100, +100]` / `[-1, +1]`. `+` = calls bought / puts sold.
- `direction` — `"bullish"` | `"bearish"` | `"neutral"` (sign of score).
- `call_net_premium` / `put_net_premium` — USD, signed. `+` = net aggressor buying.
- `source` — `"flow_by_type"` (data present) | `"unavailable"` (abstained).
- `context_values` — the four per-side premium totals plus `source`.
- `score_history` — up to 90 recent `{score, timestamp}` points, newest→oldest.

**Trader interpretation.**
- `score > +50` with flat price → early bullish accumulation; potential breakout.
- `score < −50` with flat price → early distribution; watch for breakdown.
- Score **sign-flips** while price keeps trending → exhaustion warning.
- Score ≈ 0 during market hours with `source="unavailable"` → thin tape, not neutral.

**Page design.** Horizontal bidirectional bar (−100 → +100) with center
needle, green right / red left. Below: stacked bar of the four premium
components so the trader sees *which side* drives the imbalance.
Sparkline of `score_history` (90 pts) beneath. Footer chip shows `source`.

## 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)