{
"symbol": "SPY",
"lookback_days": 90,
"snapshots_available": 0,
"period_flows": [
{
"from_date": "2026-04-30",
"to_date": "2026-05-31",
"from_nav": 0,
"to_nav": 0,
"delta_shares": 0,
"net_flow_dollar_estimate": 0
}
],
"total_net_flow_dollar_estimate": 0,
"methodology": "string"
}