diff --git a/application/runtime_strategy_adapters.py b/application/runtime_strategy_adapters.py
index 277cf6b..17534c9 100644
--- a/application/runtime_strategy_adapters.py
+++ b/application/runtime_strategy_adapters.py
@@ -48,14 +48,26 @@ def _bar_size_to_yfinance_interval(bar_size: str) -> str:
     return "1d"
 
 
-def _frame_column(frame: pd.DataFrame, name: str):
+def _coerce_frame_selection_to_series(selection: Any) -> pd.Series | None:
+    if isinstance(selection, pd.Series):
+        return selection
+    if isinstance(selection, pd.DataFrame) and len(selection.columns) > 0:
+        return selection.iloc[:, 0]
+    return None
+
+
+def _frame_column(frame: pd.DataFrame, name: str) -> pd.Series | None:
     if name in frame.columns:
-        return frame[name]
+        series = _coerce_frame_selection_to_series(frame[name])
+        if series is not None:
+            return series
     if isinstance(frame.columns, pd.MultiIndex):
         expected = name.lower()
         for column in frame.columns:
             if any(str(part).lower() == expected for part in column):
-                return frame[column]
+                series = _coerce_frame_selection_to_series(frame[column])
+                if series is not None:
+                    return series
     return None
 
 
diff --git a/tests/test_runtime_strategy_adapters.py b/tests/test_runtime_strategy_adapters.py
index cfe1190..c831d1b 100644
--- a/tests/test_runtime_strategy_adapters.py
+++ b/tests/test_runtime_strategy_adapters.py
@@ -2,7 +2,7 @@
 
 import pandas as pd
 
-from application.runtime_strategy_adapters import build_runtime_strategy_adapters
+from application.runtime_strategy_adapters import _coerce_yfinance_candles, build_runtime_strategy_adapters
 
 
 def test_strategy_plugin_signals_are_loaded_reported_and_rendered():
@@ -98,6 +98,31 @@ def test_historical_candles_fall_back_when_ibkr_history_is_empty():
     assert adapters.get_historical_candles("fake-ib", "QQQ") == fallback
 
 
+def test_yfinance_candle_coercion_handles_single_symbol_multiindex_columns():
+    frame = pd.DataFrame(
+        [[100.0, 101.0, 102.0, 99.0, 1_000_000.0]],
+        index=pd.to_datetime(["2026-05-22"]),
+        columns=pd.MultiIndex.from_tuples(
+            [
+                ("Open", "QQQ"),
+                ("Close", "QQQ"),
+                ("High", "QQQ"),
+                ("Low", "QQQ"),
+                ("Volume", "QQQ"),
+            ]
+        ),
+    )
+
+    candles = _coerce_yfinance_candles(frame)
+
+    assert len(candles) == 1
+    assert candles[0]["open"] == 100.0
+    assert candles[0]["close"] == 101.0
+    assert candles[0]["high"] == 102.0
+    assert candles[0]["low"] == 99.0
+    assert candles[0]["volume"] == 1_000_000.0
+
+
 def test_strategy_plugin_true_crisis_builds_escalated_alert_message():
     translations = {
         "strategy_plugin_line": "plugin={plugin}|mode={mode}|route={route}|action={action}",