Quick start

1. Configure a token

Create a MobiusQuant token and keep it in an environment variable:

export MOBIUSQUANT_TOKEN='mq_xxx'

Never place a real token in source code or browser JavaScript.

2. Read the ETF overview

The overview is the shortest path to the latest flow direction, its current streak, and the long-term-capital proxy:

curl --fail --silent --show-error \
  -H "Authorization: Bearer ${MOBIUSQUANT_TOKEN}" \
  "https://api.mobiusquant.ai/api/wgo/v1/etf/BTC/overview?window=30"

Key fields:

{
  "symbol": "BTC",
  "as_of": "2026-08-21",
  "observations": 30,
  "latest": {
    "net_inflow": "307453306.12",
    "direction": "inflow",
    "settlement_status": "settled"
  },
  "flow_streak": {
    "direction": "inflow",
    "days": 3
  },
  "period": {
    "net_inflow": "1430936317.58",
    "inflow_days": 18,
    "outflow_days": 12,
    "flat_days": 0
  },
  "long_term_capital_proxy": {
    "basis": "change_in_cumulative_net_inflow",
    "direction": "increased",
    "cumulative_net_inflow_change": "913743812.30",
    "from": "2026-07-13",
    "to": "2026-08-21"
  }
}

The values above illustrate the response shape. Always use as_of from the live response rather than assuming it represents the current calendar date.

3. Interpret the result

• latest.direction answers whether the latest settled ETF day was an inflow or outflow.
• flow_streak answers whether that direction has persisted over consecutive ETF observations.
• period describes the requested rolling window.
• long_term_capital_proxy.direction answers whether cumulative net inflow rose or fell across the window.

The proxy measures capital-flow persistence. It does not identify a holder, market maker, institution, or individual investor.

4. Drill down only when needed

Fetch the daily series:

curl --fail --silent --show-error \
  -H "Authorization: Bearer ${MOBIUSQUANT_TOKEN}" \
  "https://api.mobiusquant.ai/api/wgo/v1/etf/BTC/daily?limit=30"

Fetch the latest settled per-fund breakdown:

curl --fail --silent --show-error \
  -H "Authorization: Bearer ${MOBIUSQUANT_TOKEN}" \
  "https://api.mobiusquant.ai/api/wgo/v1/etf/BTC/funds"

Replace BTC with ETH for Ethereum ETF data.