diff --git a/apps/intraday_bt/scripts/diag_orb_sector_etf.py b/apps/intraday_bt/scripts/diag_orb_sector_etf.py
new file mode 100644
index 0000000..542106a
--- /dev/null
+++ b/apps/intraday_bt/scripts/diag_orb_sector_etf.py
@@ -0,0 +1,440 @@
+"""
+V45 Diagnostic: Sector ETF Gap Signal
+
+Hypothesis: On days when the stock's sector ETF (XLK, XLF, etc.) itself has a positive
+morning gap (open > prior close), individual ORB breakouts in that sector have stronger
+follow-through. The logic: if XLK gaps up while NVDA gaps up, it's a sector-wide
+institutional move with more follow-through than an idiosyncratic NVDA gap.
+
+Features tested:
+  sector_etf_gap_pct    : (sector_etf_open - sector_etf_prev_close) / sector_etf_prev_close
+  sector_etf_orb_return : sector ETF return during its own 5-min ORB window
+  sector_minus_qqq_gap  : sector_etf_gap_pct - qqq_gap_pct (sector-relative strength)
+
+Source: V24 400d run JSON + fetched sector ETF parquet data.
+
+Sector → ETF mapping (SPDR Select Sectors):
+  Technology         → XLK
+  Financial Services → XLF
+  Healthcare         → XLV
+  Energy             → XLE
+  Industrials        → XLI
+  Basic Materials    → XLB
+  Communication Services → XLC
+  Utilities          → XLU
+  Real Estate        → XLRE
+  Consumer Defensive → XLP
+  Consumer Cyclical  → XLY
+"""
+from __future__ import annotations
+
+import concurrent.futures
+import datetime as dt
+import json
+import os
+import sys
+from pathlib import Path
+
+import pyarrow.parquet as pq
+
+sys.path.insert(0, os.path.abspath(os.path.join(os.path.dirname(__file__), "../../..")))
+
+from zoneinfo import ZoneInfo
+from libs.common.time_utils import trading_days_between
+
+_ET = ZoneInfo("America/New_York")
+_MKT_OPEN = dt.time(9, 30)
+_ORB_END = dt.time(9, 35)  # 5-min ORB end
+_MKT_CLOSE = dt.time(16, 0)
+
+INTRADAY_CACHE_DIR = "data/cache/intraday"
+V24_400D_RUN = "runs/intraday_orb/intraday_20260422_011012_06f59ede.json"
+SECTOR_CACHE = "data/cache/sector_cache.json"
+
+SECTOR_TO_ETF: dict[str, str] = {
+    "Technology": "XLK",
+    "Financial Services": "XLF",
+    "Healthcare": "XLV",
+    "Energy": "XLE",
+    "Industrials": "XLI",
+    "Basic Materials": "XLB",
+    "Communication Services": "XLC",
+    "Utilities": "XLU",
+    "Real Estate": "XLRE",
+    "Consumer Defensive": "XLP",
+    "Consumer Cyclical": "XLY",
+}
+
+# Also track QQQ for sector-relative comparison
+ETF_TICKERS = list(set(SECTOR_TO_ETF.values())) + ["QQQ"]
+
+
+def _parse_ts(ts_raw: object) -> dt.datetime:
+    s = str(ts_raw)
+    if s.endswith("Z"):
+        s = s[:-1] + "+00:00"
+    return dt.datetime.fromisoformat(s).astimezone(_ET)
+
+
+def fetch_and_cache_etf_bars(tickers: list[str], start_date: str, end_date: str) -> None:
+    """Fetch intraday bars for sector ETFs and save to parquet cache."""
+    import httpx
+    import pyarrow as pa
+
+    base_url = "http://localhost:18001"
+
+    def _fetch_one(ticker: str) -> tuple[str, list[dict]]:
+        url = base_url + "/api/v1/alpaca/intraday"
+        try:
+            resp = httpx.get(
+                url,
+                params={"tickers": ticker, "interval": "5min",
+                        "start_date": start_date, "end_date": end_date},
+                timeout=120.0,
+            )
+            resp.raise_for_status()
+            return ticker, resp.json().get("bars", {}).get(ticker, [])
+        except Exception as exc:
+            print(f"  WARNING: failed to fetch {ticker}: {exc}")
+            return ticker, []
+
+    bars_by_ticker: dict[str, list[dict]] = {}
+    for ticker in tickers:
+        print(f"  Fetching {ticker}...", end=" ", flush=True)
+        _, bars = _fetch_one(ticker)
+        if bars:
+            bars_by_ticker[ticker] = bars
+            print(f"{len(bars)} bars")
+        else:
+            print("FAILED")
+
+    schema = pa.schema(
+        [
+            ("timestamp", pa.string()),
+            ("open", pa.float64()),
+            ("high", pa.float64()),
+            ("low", pa.float64()),
+            ("close", pa.float64()),
+            ("volume", pa.int64()),
+        ]
+    )
+
+    for ticker, bars in bars_by_ticker.items():
+        # Group bars by date
+        by_date: dict[str, list[dict]] = {}
+        for bar in bars:
+            try:
+                ts = _parse_ts(bar["timestamp"])
+            except Exception:
+                continue
+            date_str = ts.date().isoformat()
+            by_date.setdefault(date_str, []).append(bar)
+
+        saved = 0
+        for date_str, day_bars in by_date.items():
+            path = Path(INTRADAY_CACHE_DIR) / ticker.upper() / f"{date_str}.parquet"
+            if path.exists():
+                continue
+            path.parent.mkdir(parents=True, exist_ok=True)
+            rows = {
+                "timestamp": [],
+                "open": [],
+                "high": [],
+                "low": [],
+                "close": [],
+                "volume": [],
+            }
+            for b in day_bars:
+                rows["timestamp"].append(str(b.get("timestamp", "")))
+                rows["open"].append(float(b.get("open", 0) or 0))
+                rows["high"].append(float(b.get("high", 0) or 0))
+                rows["low"].append(float(b.get("low", 0) or 0))
+                rows["close"].append(float(b.get("close", 0) or 0))
+                rows["volume"].append(int(b.get("volume", 0) or 0))
+            table = pa.table(rows, schema=schema)
+            pq.write_table(table, str(path))
+            saved += 1
+        print(f"  {ticker}: {saved} new parquet files saved")
+
+    missing = [t for t in tickers if t not in bars_by_ticker]
+    if missing:
+        print(f"  WARNING: no data returned for {missing}")
+
+
+def load_etf_daily_ohlcv(ticker: str, dates: list[str]) -> dict[str, dict]:
+    """Load OHLCV data for each trading day. Returns {date: {open, close, orb_high, orb_return}}."""
+    result = {}
+    for date in dates:
+        path = Path(INTRADAY_CACHE_DIR) / ticker.upper() / f"{date}.parquet"
+        if not path.exists():
+            continue
+        try:
+            table = pq.read_table(str(path))
+            rows = table.to_pydict()
+        except Exception:
+            continue
+
+        # Parse all bars, collect opens/closes and ORB bar
+        mkt_bars = []
+        for i, ts_raw in enumerate(rows.get("timestamp", [])):
+            try:
+                ts = _parse_ts(ts_raw)
+            except Exception:
+                continue
+            if not (_MKT_OPEN <= ts.time() < _MKT_CLOSE):
+                continue
+            mkt_bars.append(
+                {
+                    "ts": ts,
+                    "open": float(rows["open"][i] or 0),
+                    "high": float(rows["high"][i] or 0),
+                    "low": float(rows["low"][i] or 0),
+                    "close": float(rows["close"][i] or 0),
+                }
+            )
+
+        if not mkt_bars:
+            continue
+        mkt_bars.sort(key=lambda b: b["ts"])
+
+        day_open = mkt_bars[0]["open"]
+        day_close = mkt_bars[-1]["close"]
+
+        # 5-min ORB bar (9:30-9:35): first bar
+        orb_bar = mkt_bars[0]
+        orb_high = orb_bar["high"]
+        orb_close = orb_bar["close"]
+        orb_open = orb_bar["open"]
+        orb_return = (orb_close - orb_open) / orb_open if orb_open > 0 else None
+
+        result[date] = {
+            "open": day_open,
+            "close": day_close,
+            "orb_high": orb_high,
+            "orb_return": orb_return,
+        }
+    return result
+
+
+def pearson(xs: list[float], ys: list[float]) -> float | None:
+    n = len(xs)
+    if n < 2:
+        return None
+    xm, ym = sum(xs) / n, sum(ys) / n
+    num = sum((xs[i] - xm) * (ys[i] - ym) for i in range(n))
+    dx = sum((x - xm) ** 2 for x in xs) ** 0.5
+    dy = sum((y - ym) ** 2 for y in ys) ** 0.5
+    if dx <= 0 or dy <= 0:
+        return None
+    return num / (dx * dy)
+
+
+def tercile_stats(vals: list[float], rs: list[float]) -> dict:
+    if len(vals) < 9:
+        return {}
+    pairs = sorted(zip(vals, rs), key=lambda p: p[0])
+    n = len(pairs)
+    t = n // 3
+    def stats(sub):
+        ys = [p[1] for p in sub]
+        return {"n": len(ys), "wr": sum(1 for y in ys if y > 0) / len(ys), "avg_r": sum(ys) / len(ys)}
+    return {"low": stats(pairs[:t]), "mid": stats(pairs[t:2*t]), "high": stats(pairs[2*t:])}
+
+
+def report_feature(label: str, vals: list[float], rs: list[float], obv_vals: list[float] | None = None) -> None:
+    n = len(vals)
+    p = pearson(vals, rs)
+    ts = tercile_stats(vals, rs)
+    if not ts or p is None:
+        print(f"  {label}: n={n}, insufficient data")
+        return
+    low, mid, high = ts["low"], ts["mid"], ts["high"]
+    avg_r_gap = abs(high["avg_r"] - low["avg_r"])
+    wr_gap = abs(high["wr"] - low["wr"])
+    g1 = abs(p) >= 0.07 and n >= 120
+    g2 = avg_r_gap >= 0.30
+    g3 = wr_gap >= 0.05
+
+    # G5a: redundancy with OBV slope
+    g5a = True
+    rho_obv = None
+    if obv_vals is not None and len(obv_vals) == n:
+        rho_obv = pearson(vals, obv_vals)
+        if rho_obv is not None:
+            g5a = abs(rho_obv) < 0.70
+
+    print(f"\n  [{label}]  n={n}  Pearson={p:+.3f}")
+    print(f"    G1: {'PASS' if g1 else 'FAIL'} (|{abs(p):.3f}| {'≥' if abs(p)>=0.07 else '<'} 0.07, n={n})")
+    print(f"    G2: {'PASS' if g2 else 'FAIL'} (avg_R gap = {avg_r_gap:.3f}R  [threshold 0.30R])")
+    print(f"    G3: {'PASS' if g3 else 'FAIL'} (WR gap = {wr_gap*100:.1f}pp  [threshold 5pp])")
+    if rho_obv is not None:
+        print(f"    G5a: {'PASS' if g5a else 'FAIL'} (ρ(feature,OBV-slope)={rho_obv:+.3f}  [threshold |<0.70|])")
+    print(f"    Bottom tercile: WR {low['wr']*100:.1f}%  avg_R {low['avg_r']:+.3f}  n={low['n']}")
+    print(f"    Middle tercile: WR {mid['wr']*100:.1f}%  avg_R {mid['avg_r']:+.3f}  n={mid['n']}")
+    print(f"    Top tercile:    WR {high['wr']*100:.1f}%  avg_R {high['avg_r']:+.3f}  n={high['n']}")
+    all_gates = g1 and g2 and g3 and g5a
+    print(f"    → {'ALL GATES PASS ✓' if all_gates else 'FAIL'}")
+
+
+def main() -> None:
+    print("=== V45 Sector ETF Gap Signal Diagnostic ===\n")
+
+    # Load V24 400d run
+    with open(V24_400D_RUN) as f:
+        run_data = json.load(f)
+    trades = run_data.get("trades", [])
+    m = run_data.get("metrics", {})
+    print(f"Loaded V24 400d: {m.get('total_trades')} trades, {m.get('start_date')} → {m.get('end_date')}")
+
+    # Load sector cache
+    with open(SECTOR_CACHE) as f:
+        sector_cache = json.load(f)
+
+    trade_records = [
+        {
+            "ticker": t["ticker"],
+            "date": t["date"][:10],
+            "r_multiple": float(t["r_multiple_at_exit"]),
+            "sector": sector_cache.get(t["ticker"], "UNKNOWN"),
+        }
+        for t in trades
+        if t.get("r_multiple_at_exit") is not None
+    ]
+
+    # Date range
+    all_dates_in_trades = sorted(set(r["date"] for r in trade_records))
+    min_d = dt.date.fromisoformat(min(all_dates_in_trades))
+    max_d = dt.date.fromisoformat(max(all_dates_in_trades))
+    # Need prior-day data — go back 1 extra trading day
+    start_d = min_d - dt.timedelta(days=5)
+    all_td = trading_days_between(start_d, max_d)
+    all_dates = [d.isoformat() for d in all_td]
+
+    # Check which ETF dates are missing from cache
+    missing_etfs = []
+    for etf in ETF_TICKERS:
+        etf_dir = Path(INTRADAY_CACHE_DIR) / etf.upper()
+        cached_dates = set(f.stem for f in etf_dir.glob("*.parquet")) if etf_dir.exists() else set()
+        needed = [d for d in all_dates if d not in cached_dates]
+        if needed:
+            missing_etfs.append((etf, needed))
+
+    if missing_etfs:
+        print(f"\nFetching missing sector ETF data ({len(missing_etfs)} ETFs need data)...")
+        tickers_to_fetch = [e for e, _ in missing_etfs]
+        start_str = start_d.isoformat()
+        end_str = max_d.isoformat()
+        fetch_and_cache_etf_bars(tickers_to_fetch, start_str, end_str)
+    else:
+        print(f"\nAll sector ETF data already cached ({len(ETF_TICKERS)} ETFs).")
+
+    # Load daily OHLCV for all sector ETFs + QQQ
+    print(f"\nLoading ETF daily data ({len(all_dates)} trading days)...")
+    etf_daily: dict[str, dict[str, dict]] = {}
+    for etf in ETF_TICKERS:
+        etf_daily[etf] = load_etf_daily_ohlcv(etf, all_dates)
+        print(f"  {etf}: {len(etf_daily[etf])} days loaded")
+
+    # Build OBV slope reference for G5a redundancy check
+    # We'll use the obv_slope_20 from V24 run's enrichment if available, otherwise skip G5a
+    obv_by_record: list[float | None] = []
+
+    # Compute features for each trade
+    sector_gap_vals: list[float] = []
+    sector_orb_ret_vals: list[float] = []
+    sector_minus_qqq_vals: list[float] = []
+    r_mults: list[float] = []
+    obv_paired: list[float] = []
+    missing = 0
+
+    for rec in trade_records:
+        date = rec["date"]
+        sector = rec["sector"]
+        etf = SECTOR_TO_ETF.get(sector)
+        r = rec["r_multiple"]
+
+        if etf is None:
+            missing += 1
+            continue
+
+        # Get prior trading day for sector ETF and QQQ
+        idx = all_dates.index(date) if date in all_dates else -1
+        if idx <= 0:
+            missing += 1
+            continue
+        prior_date = all_dates[idx - 1]
+
+        etf_data = etf_daily.get(etf, {})
+        qqq_data = etf_daily.get("QQQ", {})
+
+        today_etf = etf_data.get(date)
+        prior_etf = etf_data.get(prior_date)
+        today_qqq = qqq_data.get(date)
+        prior_qqq = qqq_data.get(prior_date)
+
+        if not today_etf or not prior_etf or prior_etf["close"] <= 0:
+            missing += 1
+            continue
+
+        # Feature 1: sector ETF morning gap (today open vs prior close)
+        etf_gap = (today_etf["open"] - prior_etf["close"]) / prior_etf["close"]
+
+        # Feature 2: sector ETF 5-min ORB return
+        etf_orb_ret = today_etf.get("orb_return")
+        if etf_orb_ret is None:
+            missing += 1
+            continue
+
+        # Feature 3: sector ETF gap relative to QQQ gap
+        if today_qqq and prior_qqq and prior_qqq["close"] > 0:
+            qqq_gap = (today_qqq["open"] - prior_qqq["close"]) / prior_qqq["close"]
+            sector_relative_gap = etf_gap - qqq_gap
+        else:
+            sector_relative_gap = None
+
+        sector_gap_vals.append(etf_gap)
+        sector_orb_ret_vals.append(etf_orb_ret)
+        r_mults.append(r)
+        if sector_relative_gap is not None:
+            sector_minus_qqq_vals.append(sector_relative_gap)
+
+    n_valid = len(r_mults)
+    print(f"\nValid trades: {n_valid} / {len(trade_records)}  (missing/unmapped: {missing})")
+
+    if sector_gap_vals:
+        mean_gap = sum(sector_gap_vals) / len(sector_gap_vals)
+        pct_positive = sum(1 for g in sector_gap_vals if g > 0) / len(sector_gap_vals)
+        print(f"Mean sector ETF gap: {mean_gap:+.2%}  (positive: {pct_positive:.1%})")
+
+    print("\n" + "=" * 60)
+    print("GATE RESULTS (G1: |P|≥0.07 & n≥120; G2: avg_R≥0.30R; G3: WR≥5pp; G5a: |ρ_OBV|<0.70)")
+
+    report_feature("sector_etf_gap_pct (morning gap vs prior close)", sector_gap_vals, r_mults)
+    report_feature("sector_etf_orb_return (ORB bar return 9:30-9:35)", sector_orb_ret_vals, r_mults)
+    if len(sector_minus_qqq_vals) >= 100:
+        report_feature(
+            "sector_minus_qqq_gap (sector ETF gap - QQQ gap)",
+            sector_minus_qqq_vals,
+            r_mults[: len(sector_minus_qqq_vals)],
+        )
+
+    # Sector breakdown: which sector ETF dominates?
+    from collections import defaultdict
+    sector_r: dict[str, list[float]] = defaultdict(list)
+    for rec in trade_records:
+        sector_r[rec["sector"]].append(rec["r_multiple"])
+    print("\n=== Per-sector breakdown ===")
+    for s in sorted(sector_r, key=lambda x: -len(sector_r[x])):
+        rs = sector_r[s]
+        etf = SECTOR_TO_ETF.get(s, "N/A")
+        wr = sum(1 for r in rs if r > 0) / len(rs)
+        avg_r = sum(rs) / len(rs)
+        print(f"  {s:28s} → {etf:5s}  n={len(rs):3d}  WR={wr:.1%}  avg_R={avg_r:+.3f}")
+
+    print("\n=== Summary ===")
+    print("G2 ≥ 0.30R is the binding gate. OBV-slope 20d passed at 0.394R (V24).")
+    print("Any feature passing ALL gates warrants Phase 2 backtest.")
+
+
+if __name__ == "__main__":
+    main()