diff --git a/src/multi_swarm/agents/market_summary.py b/src/multi_swarm/agents/market_summary.py
new file mode 100644
index 0000000..4c42117
--- /dev/null
+++ b/src/multi_swarm/agents/market_summary.py
@@ -0,0 +1,36 @@
+from __future__ import annotations
+
+import pandas as pd  # type: ignore[import-untyped]
+from scipy import stats  # type: ignore[import-untyped]
+
+from .hypothesis import MarketSummary
+
+
+def build_market_summary(
+    ohlcv: pd.DataFrame,
+    symbol: str,
+    timeframe: str,
+) -> MarketSummary:
+    returns = ohlcv["close"].pct_change().dropna()
+    return_mean = float(returns.mean())
+    return_std = float(returns.std(ddof=1))
+    skew = float(stats.skew(returns, bias=False))
+    kurt = float(stats.kurtosis(returns, fisher=True, bias=False))
+
+    if return_std < 0.005:
+        regime = "low"
+    elif return_std < 0.02:
+        regime = "medium"
+    else:
+        regime = "high"
+
+    return MarketSummary(
+        symbol=symbol,
+        timeframe=timeframe,
+        n_bars=len(ohlcv),
+        return_mean=return_mean,
+        return_std=return_std,
+        skew=skew,
+        kurtosis=kurt,
+        volatility_regime=regime,
+    )
diff --git a/tests/unit/test_market_summary.py b/tests/unit/test_market_summary.py
new file mode 100644
index 0000000..a89d640
--- /dev/null
+++ b/tests/unit/test_market_summary.py
@@ -0,0 +1,33 @@
+import numpy as np
+import pandas as pd
+
+from multi_swarm.agents.market_summary import build_market_summary
+
+
+def test_build_summary_basic() -> None:
+    idx = pd.date_range("2024-01-01", periods=200, freq="1h", tz="UTC")
+    np.random.seed(0)
+    close = 100 + np.cumsum(np.random.normal(0, 1, 200))
+    df = pd.DataFrame(
+        {"open": close, "high": close + 0.5, "low": close - 0.5, "close": close, "volume": 1.0},
+        index=idx,
+    )
+    s = build_market_summary(df, symbol="BTC/USDT", timeframe="1h")
+    assert s.symbol == "BTC/USDT"
+    assert s.timeframe == "1h"
+    assert s.n_bars == 200
+    assert isinstance(s.return_mean, float)
+    assert isinstance(s.return_std, float)
+    assert s.volatility_regime in {"low", "medium", "high"}
+
+
+def test_volatility_regime_high_for_volatile() -> None:
+    idx = pd.date_range("2024-01-01", periods=200, freq="1h", tz="UTC")
+    np.random.seed(0)
+    close = 100 + np.cumsum(np.random.normal(0, 5.0, 200))  # alta vol
+    df = pd.DataFrame(
+        {"open": close, "high": close + 0.5, "low": close - 0.5, "close": close, "volume": 1.0},
+        index=idx,
+    )
+    s = build_market_summary(df, symbol="BTC/USDT", timeframe="1h")
+    assert s.volatility_regime in {"medium", "high"}