diff --git a/haoinvest/market/sources/_common.py b/haoinvest/market/sources/_common.py
index 54a24ae..853704f 100644
--- a/haoinvest/market/sources/_common.py
+++ b/haoinvest/market/sources/_common.py
@@ -27,21 +27,23 @@ def bypass_proxy():
         os.environ.update(saved)
 
 
-def market_prefix(symbol: str) -> str:
-    """Return 'sh' or 'sz' based on A-share stock code convention."""
-    if symbol.startswith(("6", "9")):
-        return "sh"
-    return "sz"
+def _is_sh(symbol: str) -> bool:
+    """Check if symbol belongs to Shanghai Exchange.
+
+    Shanghai codes: 6xxxxx (main/STAR), 9xxxxx, 5xxxxx (ETF/funds including
+    51xxxx, 56xxxx cross-market ETFs that route via SH on quote APIs).
+    """
+    return symbol.startswith(("5", "6", "9"))
 
 
-def secid(symbol: str) -> str:
-    """Return eastmoney secid like '1.603618' (1=SH, 0=SZ)."""
-    return f"1.{symbol}" if symbol.startswith(("6", "9")) else f"0.{symbol}"
+def market_prefix(symbol: str) -> str:
+    """Return 'sh' or 'sz' based on A-share stock code convention."""
+    return "sh" if _is_sh(symbol) else "sz"
 
 
 def exchange_prefix(symbol: str) -> str:
     """Return 'SH' or 'SZ' for eastmoney web API code parameter."""
-    return "SH" if symbol.startswith(("6", "9")) else "SZ"
+    return "SH" if _is_sh(symbol) else "SZ"
 
 
 def parse_float(value: Any) -> float | None:
diff --git a/tests/test_market/test_sources/test_common.py b/tests/test_market/test_sources/test_common.py
new file mode 100644
index 0000000..6107a89
--- /dev/null
+++ b/tests/test_market/test_sources/test_common.py
@@ -0,0 +1,61 @@
+"""Tests for market source common utilities — prefix routing."""
+
+import pytest
+
+from haoinvest.market.sources._common import (
+    exchange_prefix,
+    market_prefix,
+)
+
+
+class TestMarketPrefix:
+    """Verify symbol-to-exchange prefix routing."""
+
+    @pytest.mark.parametrize(
+        "symbol,expected",
+        [
+            # Shanghai main board
+            ("600519", "sh"),
+            ("601877", "sh"),
+            # Shanghai STAR board
+            ("688001", "sh"),
+            # Shanghai ETF (51xxxx)
+            ("511360", "sh"),
+            ("513130", "sh"),
+            ("518880", "sh"),
+            # Cross-market ETF (56xxxx) — must route via sh
+            ("563020", "sh"),
+            ("560010", "sh"),
+            # Shenzhen main board
+            ("000001", "sz"),
+            ("000988", "sz"),
+            # Shenzhen SME
+            ("002001", "sz"),
+            ("002463", "sz"),
+            # Shenzhen ChiNext
+            ("300750", "sz"),
+            # Shanghai B-share
+            ("900001", "sh"),
+            # Shenzhen ETF (15xxxx)
+            ("159915", "sz"),
+        ],
+    )
+    def test_market_prefix(self, symbol: str, expected: str) -> None:
+        assert market_prefix(symbol) == expected
+
+
+class TestExchangePrefix:
+    """Verify eastmoney exchange prefix mapping."""
+
+    @pytest.mark.parametrize(
+        "symbol,expected",
+        [
+            ("600519", "SH"),
+            ("563020", "SH"),
+            ("518880", "SH"),
+            ("000988", "SZ"),
+            ("002463", "SZ"),
+        ],
+    )
+    def test_exchange_prefix(self, symbol: str, expected: str) -> None:
+        assert exchange_prefix(symbol) == expected