---
title: "Api V2 Signals Basic Tape-Flow-Bias Get"
method: GET
path: "/api/v2/signals/basic/tape-flow-bias"
tags: ["Trade Signals (v2)"]
---

# Api V2 Signals Basic Tape-Flow-Bias Get

`GET /api/v2/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/v2/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

- EnvelopeAny
  - `data` unknown, required
  - `freshness` Freshness, required: The v2 freshness envelope. Present on every ``/api/v2/*`` response.
    - `evaluated_at` string, date-time, required: When the API evaluated this response (server wall clock, UTC). Endpoint-health signal: advances on every request even when the underlying data is unchanged.
    - `generated_at` string, date-time, required: When the served data was computed. Equals the snapshot stamp for cycle-backed endpoints, or evaluated_at for endpoints computed on demand for this request.
    - `source_timestamp` string, date-time, nullable: Timestamp of the upstream market observation the payload derives from. This is what freshness_status is measured against. Null when the endpoint has no upstream feed or returned no rows.
    - `latest_event_at` string, date-time, nullable: Newest event timestamp present in the payload (last bar, last trade, last scored row). Best-effort on very large responses, which are sampled rather than fully walked.
    - `age_seconds` number, nullable: evaluated_at - source_timestamp, in seconds. Null when source_timestamp is null.
    - `market_session_status` string, required: pre-market | regular | after-hours | closed (US/Eastern).
    - `expected_update_cadence` string, nullable: ISO-8601 duration for how often this endpoint's data is expected to change right now, e.g. PT60S. Null means no updates are expected (weekend, holiday, or a feed that only runs during the session).
    - `expected_update_cadence_seconds` number, nullable: expected_update_cadence as a number of seconds.
    - `cadence_profile` string, required: Identifier of the cadence class this endpoint belongs to, e.g. analytics_cycle. Stable across releases; the seconds behind it may be retuned.
    - `stale_after` string, date-time, nullable: Instant after which this payload should be treated as stale. Null whenever expected_update_cadence is null.
    - `freshness_status` 'fresh' | 'aging' | 'stale' | 'session_closed' | 'static' | 'unknown', required: The rolled-up freshness verdict for one response. ``fresh`` ``source_timestamp`` is within one expected update cadence. ``aging`` Past one cadence but not yet past ``stale_after`` — the grace band that absorbs normal cycle jitter. Not an error; a client that polls faster than the cadence sees this routinely. ``stale`` Past ``stale_after`` while updates *were* expected. This is the actionable state: the feed behind this endpoint is late. ``session_closed`` A feed-backed endpoint whose feed is not due to produce anything right now (weekend, holiday, or a feed that only runs during the session). The payload is the last good value — deliberately NOT reported as ``stale``, because an overnight consumer polling a closed market is not observing a fault and should not page on it. ``static`` The endpoint is not feed-backed at all: completed history, or a result computed from the caller's own inputs. Age here carries no health meaning and never becomes a fault. ``unknown`` No source timestamp could be resolved from the payload (e.g. a pure calculator, an admin endpoint, or an empty result set). A consumer should fall back to ``evaluated_at`` for endpoint health and make no claim about data age.

## Other responses

- `422`: Validation Error

---

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