Endpoint

GET /v1/flow/oi/{symbol}

Auth required (X-Api-Key) Rate Limited: Yes Alpha plan+

Parameters

Name	In	Required	Default	Description
`symbol`	path	yes	-	Underlying symbol
`expiry`	query	no	all expiries	Filter chain to a single expiry (`yyyy-MM-dd`). Omit to aggregate across all expiries

curl -H "X-Api-Key: YOUR_API_KEY" \
  "https://lab.flashalpha.com/v1/flow/oi/SPY"

import requests

resp = requests.get(
    "https://lab.flashalpha.com/v1/flow/oi/SPY",
    headers={"X-Api-Key": "YOUR_API_KEY"}
)
data = resp.json()
print(f"Official OI:  {data['official_oi']:,}")
print(f"Effective OI: {data['effective_oi']:,}")
print(f"Intraday delta: {data['intraday_oi_delta']:,}")

const resp = await fetch(
  "https://lab.flashalpha.com/v1/flow/oi/SPY",
  { headers: { "X-Api-Key": "YOUR_API_KEY" } }
);
const data = await resp.json();
console.log(`Official OI:  ${data.official_oi.toLocaleString()}`);
console.log(`Effective OI: ${data.effective_oi.toLocaleString()}`);
console.log(`Intraday delta: ${data.intraday_oi_delta.toLocaleString()}`);

API Key

Response

{
  "symbol": "SPY",
  "as_of": "2026-05-12T18:42:10Z",
  "expiry": "2026-05-15",
  "official_oi": 14820000,
  "simulated_oi": 14832450,
  "intraday_oi_delta": 12450,
  "oi_delta_confidence": 0.43,
  "effective_oi": 14835100,
  "contracts_total": 5240,
  "contracts_with_flow": 1820
}

Key Response Fields

Field	Type	Description
`official_oi`	number	Sum of morning OPRA-broadcast OI across the chain
`simulated_oi`	number	`official + intraday_oi_delta` aggregated (unclamped, surfaces overshoot)
`intraday_oi_delta`	number	Sum of the simulator's signed per-contract delta. Never reconstructed from `(effective - official)` - that loses magnitude when a per-contract value overshot zero and got clamped
`oi_delta_confidence`	number	Per-trade confidence weight applied by the upstream simulator (currently `0.43`)
`effective_oi`	number	Sum of per-contract `max(0, official + delta)` - what the analytics endpoints actually consume
`contracts_with_flow`	number	Number of contracts where `intraday_delta != 0`

effective_oi can differ from max(0, simulated_oi) because the clamp is applied per-contract before aggregation.

About Flow OI

Flow OI exposes the raw simulator state that powers the rest of the /v1/flow/* family. official_oi matches the morning OPRA-broadcast OI used by the settled /v1/exposure/* endpoints. effective_oi is the per-contract clamped quantity the live analytics consume, and simulated_oi is the unclamped aggregate, which can deviate when sell pressure overshoots a contract's OI to zero. The intraday_oi_delta is the true signed sum from the simulator and intentionally cannot be reconstructed from (effective - official) - use this field if you're building your own analytics on top of the simulator.

Common Use Cases

Build custom analytics - drive your own GEX/DEX or pin-risk variants off effective_oi, the same per-contract clamped quantity the live Flow endpoints consume
Audit and reconcile - surface the gap between official_oi, simulated_oi, and effective_oi to catch overshoot or clamping artefacts before they reach exposure numbers
Read directional flow - the sign of intraday_oi_delta shows whether the day is net opening or net closing interest, the input to opening-vs-closing bias
Weight by confidence - scale signal size by oi_delta_confidence and de-rate the read when the simulator is less certain about the intraday delta
Gauge session breadth - contracts_with_flow / contracts_total is a rough activity-heat measure for how much of the chain is repositioning
Power research workflows - pair with historical exposure snapshots to study how intraday OI flow predicts end-of-day positioning

Complementary endpoints

OI Diff - day-over-day open-interest changes by strike
Flow Live Bundle - the raw real-time tape feeding the simulator
Flow GEX - live flow-adjusted gamma built on this effective OI

Flow OI API