diff --git a/backend/app/infrastructure/persistence/sqlalchemy/repositories/market_impl.py b/backend/app/infrastructure/persistence/sqlalchemy/repositories/market_impl.py
index 98943c0..886c7a3 100644
--- a/backend/app/infrastructure/persistence/sqlalchemy/repositories/market_impl.py
+++ b/backend/app/infrastructure/persistence/sqlalchemy/repositories/market_impl.py
@@ -10,6 +10,7 @@ from __future__ import annotations
 
 from collections.abc import Sequence
 from datetime import date
+from typing import Any
 
 from sqlalchemy import select
 from sqlalchemy.orm import Session
@@ -54,30 +55,44 @@ def _upsert_by_business_key(
     entity_cls,
     entities: Sequence,
 ) -> int:
-    """按业务幂等键查重后 insert/update，返回触及行数（新增+更新）。
+    """按业务幂等键**批量**查重后 insert/update（AGENT.md §1 性能友好：不做逐行 select）。
 
-    同一批内出现重复键（数据源偶发）时：先 flush 使前面已 add 的行可见，
-    再按「后出现者覆盖」更新为最新值，避免 UNIQUE 冲突。
+    - 一次查询取出本批已有的键 → 新行批量 add，已有行就地更新
+    - 同一批内重复键（数据源偶发）：以「后出现者」为准覆盖（避免 UNIQUE 冲突）
+    - 返回处理实体总数（含新增与更新），与旧逐行实现语义一致
     """
+    if not entities:
+        return 0
     model_cls, key_cols = _TABLE[entity_cls]
-    seen: set[tuple] = set()
-    touched = 0
+    key_col_attrs = [getattr(model_cls, k) for k in key_cols]
+
+    keyed: list[tuple[tuple, dict]] = []
     for ent in entities:
         values = _fields_of(ent)
-        key = tuple(values[k] for k in key_cols)
-        if key in seen:
-            session.flush()  # 让本批内先前新增的行进入 select 视野
-        else:
-            seen.add(key)
-        filters = [getattr(model_cls, k) == values[k] for k in key_cols]
-        row = session.scalars(select(model_cls).where(*filters)).first()
+        keyed.append((tuple(values[k] for k in key_cols), values))
+
+    existing_rows: dict[tuple, Any] = {}
+    keys = [k for k, _v in keyed]
+    if keys:
+        from sqlalchemy import tuple_
+
+        stmt = select(model_cls).where(tuple_(*key_col_attrs).in_(keys))
+        for row in session.scalars(stmt):
+            key = tuple(getattr(row, k) for k in key_cols)
+            existing_rows[key] = row
+
+    pending: dict[tuple, Any] = {}
+    for key, values in keyed:
+        row = existing_rows.get(key)
+        if row is None and key in pending:
+            row = pending[key]  # 批内已待插入的同键 → 覆盖为新值
         if row is None:
-            session.add(model_cls(**values))
+            pending[key] = model_cls(**values)
         else:
             for col, val in values.items():
                 setattr(row, col, val)
-        touched += 1
-    return touched
+    session.add_all(pending.values())
+    return len(keyed)
 
 
 class SqlAlchemyStockRepository: