diff --git a/trace_agg/src/trace_agg/core.py b/trace_agg/src/trace_agg/core.py
new file mode 100644
index 0000000..9479734
--- /dev/null
+++ b/trace_agg/src/trace_agg/core.py
@@ -0,0 +1,57 @@
+import pandas as pd
+import numpy as np
+import os
+from pathlib import Path
+from statistics import median
+
+
+def aggregate_em_data(num_trials: int) -> dict:
+    """Aggregiert EM-Daten aus CSV-Dateien und berechnet Summary-Kennzahlen.
+
+    Args:
+        num_trials (int): Anzahl der zu verarbeitenden Trials/Samples.
+
+    Returns:
+        dict: Dictionary im Schema von summary_statistics mit
+              peak_amplitude, median_bandpower, crosscorr_with_clockevents.
+    """
+    data_dir = Path('data')
+    csv_files = sorted(data_dir.glob('em_traces_*.csv'))
+    if not csv_files:
+        raise FileNotFoundError("Keine Eingabedateien gefunden unter data/em_traces_*.csv")
+
+    all_data = []
+    for i, csv_path in enumerate(csv_files):
+        if num_trials and i >= num_trials:
+            break
+        df = pd.read_csv(csv_path)
+        # Validierung der erwarteten Spalten
+        for col in ('timestamp', 'amplitude', 'bandpower'):
+            if col not in df.columns:
+                raise ValueError(f"Fehlende Spalte '{col}' in {csv_path.name}")
+        all_data.append(df)
+
+    if not all_data:
+        raise ValueError("Keine gültigen EM-Daten gefunden.")
+
+    combined = pd.concat(all_data, ignore_index=True)
+
+    # Berechnungen
+    peak_amplitude = float(combined['amplitude'].max()) if not combined.empty else 0.0
+    median_bandpower = float(combined['bandpower'].median()) if not combined.empty else 0.0
+
+    # Vereinfachte Crosscorrelation-Metrik (Amplitude vs. Bandpower)
+    if len(combined) > 1:
+        crosscorr_value = float(np.corrcoef(combined['amplitude'], combined['bandpower'])[0, 1])
+        if np.isnan(crosscorr_value):
+            crosscorr_value = 0.0
+    else:
+        crosscorr_value = 0.0
+
+    summary = {
+        "peak_amplitude": peak_amplitude,
+        "median_bandpower": median_bandpower,
+        "crosscorr_with_clockevents": crosscorr_value,
+    }
+
+    return summary