# Upside/Downside Capture API > Measures the asymmetry every allocator actually cares about: how much of a benchmark's gains an asset captures when the market rises, versus how much of its losses it suffers when the market falls — computed live from Yahoo Finance daily closes, no key, nothing stored. A single beta assumes a market moves the same up and down, but the assets worth owning do not: they participate in rallies and cushion sell-offs, and the ones to avoid do the opposite. This API splits the benchmark's history into up-days and down-days and measures each side separately. The upside capture is the asset's average gain on the benchmark's up-days relative to the benchmark (above 100 = it gains more than the market in rallies); the downside capture is the same on down-days (below 100 = it loses less in sell-offs — defensive). Their ratio, the capture ratio, is the headline: above 1 means a favourable asymmetry. It also returns the downside beta and upside beta — the asset's beta measured only on the benchmark's down- and up-days — whose gap reveals whether the asset is more exposed in crashes than in rallies. The asset endpoint returns one instrument's full asymmetry profile; the screener endpoint ranks the cross-asset universe by capture ratio, downside capture or downside beta. This is the conditional / up-down asymmetry cut — distinct from the single unconditional beta screener, the correlation matrix, and the total-risk and tail-risk APIs. It separates the up market from the down market. ## Authentication All requests require your oanor API key in the `x-oanor-key` header. Get one at https://www.oanor.com/developer/keys. ```bash curl -H "x-oanor-key: oanor_live_…" "https://api.oanor.com/capture-api/..." ``` ## Pricing - **Free** (Free) — 685 calls/Mo, 2 req/s - **Starter** ($11/Mo) — 15,300 calls/Mo, 6 req/s - **Pro** ($37/Mo) — 87,000 calls/Mo, 16 req/s - **Mega** ($82/Mo) — 476,000 calls/Mo, 40 req/s ## Endpoints ### Screener #### `GET /v1/screener` — Rank the universe by up/down capture asymmetry **Parameters:** - `benchmark` (query, optional, string) — Universe symbol used as benchmark Example: `SPY` - `sort` (query, optional, string) — capture_ratio, downside_capture, upside_capture or downside_beta Example: `capture_ratio` - `window` (query, optional, string) — Lookback in trading days (60-756) Example: `252` - `class` (query, optional, string) — equity, sector, commodity, bond, crypto or all Example: `all` **Example:** ```bash curl -H "x-oanor-key: $KEY" \ "https://api.oanor.com/capture-api/v1/screener?benchmark=SPY&sort=capture_ratio&window=252&class=all" ``` **Response:** ```json { "data": { "note": "Computed vs SPY over window_days of daily returns, split into the benchmark's up- and down-days. upside_capture > 100 = gains more than the market in rallies; downside_capture < 100 = loses less in sell-offs (defensive); capture_ratio > 1 = favourable asymmetry. downside_beta > upside_beta = more exposed in crashes than rallies. Read fresh per call, nothing cached.", "class": "all", "count": 20, "source": "Yahoo Finance", "results": [ { "name": "Silver", "rank": 1, "class": "commodity", "symbol": "SLV", "up_days": 141, "available": true, "down_days": 111, "upside_beta": 1.428, "observations": 252, "capture_ratio": 1.368, "downside_beta": 1.147, "upside_capture": 209.6, "downside_capture": 153.2 }, { "name": "Utilities", "rank": 2, "class": "sector", "symbol": "XLU", "up_days": 141, "available": true, "down_days": 111, "upside_beta": 0.151, "observations": 252, "capture_ratio": 1.314, "downside_beta": 0.21, "upside_capture": 26.7, "downside_capture": 20.3 }, …(truncated, see openapi.json for full schema) ``` ### Asset #### `GET /v1/asset` — Full asymmetry profile of one instrument **Parameters:** - `symbol` (query, required, string) — Universe symbol Example: `TLT` - `benchmark` (query, optional, string) — Benchmark symbol Example: `SPY` - `window` (query, optional, string) — Lookback in trading days (60-756) Example: `252` **Example:** ```bash curl -H "x-oanor-key: $KEY" \ "https://api.oanor.com/capture-api/v1/asset?symbol=TLT&benchmark=SPY&window=252" ``` **Response:** ```json { "data": { "name": "20Y+ Treasuries", "note": "Up- and down-capture vs SPY on the benchmark's up- and down-days; capture_ratio = upside/downside. downside_beta and upside_beta are the asset's beta on down- and up-days. Read fresh per call, nothing cached.", "class": "bond", "reads": { "capture_ratio": "poor asymmetry (gives up more than it gains)", "crash_exposure": "more exposed in rallies than crashes (good asymmetry)", "downside_capture": "defensive — cushions sell-offs" }, "source": "Yahoo Finance", "symbol": "TLT", "up_days": 141, "benchmark": "SPY", "down_days": 111, "upside_beta": 0.266, "window_days": 252, "observations": 252, "capture_ratio": 0.789, "downside_beta": 0.022, "benchmark_name": "S&P 500", "upside_capture": 15, "downside_capture": 19 }, "meta": { "timestamp": "2026-06-12T10:34:46.181Z", "request_id": "11226ef6-235a-4f75-8e08-c51f82d958ea" }, "status": "ok", "message": "Asset capture retrieved successfully", "success": true } ``` ### Universe #### `GET /v1/universe` — The cross-asset universe and its classes **Example:** ```bash curl -H "x-oanor-key: $KEY" \ "https://api.oanor.com/capture-api/v1/universe" ``` **Response:** ```json { "data": { "note": "The cross-asset universe the screener ranks. Pass class= to a screener call to rank within one class.", "count": 20, "assets": [ { "name": "S&P 500", "class": "equity", "symbol": "SPY" }, { "name": "Nasdaq 100", "class": "equity", "symbol": "QQQ" }, { "name": "US Small Caps", "class": "equity", "symbol": "IWM" }, { "name": "Developed ex-US", "class": "equity", "symbol": "EFA" }, { "name": "Emerging Markets", "class": "equity", "symbol": "EEM" }, { "name": "Technology", "class": "sector", "symbol": "XLK" }, { "name": "Financials", "class": "sector", "symbol": "XLF" }, { "name": "Energy", "class": "sector", "symbol": "XLE" }, { "name": "Health Care", "class": "sector", "symbol": "XLV" }, { "name": "Utilities", "class": "sector", "symbo …(truncated, see openapi.json for full schema) ``` ### Meta #### `GET /v1/meta` — Service metadata **Example:** ```bash curl -H "x-oanor-key: $KEY" \ "https://api.oanor.com/capture-api/v1/meta" ``` **Response:** ```json { "data": { "note": "benchmark is any universe symbol (default SPY). window is 60-756 trading days (default 252). sort is capture_ratio (default), downside_capture, upside_capture or downside_beta. class filters to equity/sector/commodity/bond/crypto (default all). Read fresh per call, nothing cached.", "sorts": [ "capture_ratio", "downside_capture", "downside_beta", "upside_capture" ], "source": "Yahoo Finance daily closes, live", "classes": [ "equity", "sector", "commodity", "bond", "crypto" ], "service": "capture-api", "endpoints": { "GET /v1/meta": "This document.", "GET /v1/asset": "Full asymmetry profile of one instrument (symbol=TLT, benchmark=SPY, window=252).", "GET /v1/screener": "Rank the universe by up/down capture asymmetry (benchmark=SPY, sort=capture_ratio, window=252, class=all).", "GET /v1/universe": "The cross-asset universe and its classes." }, "description": "Upside/downside capture & downside beta — how much of a benchmark's gains an asset captures in up markets versus how much of its losses it suffers in down markets, live from Yahoo Finance daily closes (no key, nothing stored). upside_capture > 100 gains more than the market in rallies; downside_capture < 100 loses less in sell-offs; capture_ratio > 1 is favourable …(truncated, see openapi.json for full schema) ``` --- Marketplace page: https://www.oanor.com/api/capture-api OpenAPI spec: https://www.oanor.com/api/capture-api/openapi.json