diff --git a/backend/app/api/endpoints/analysis.py b/backend/app/api/endpoints/analysis.py
index c3ede59..d15f531 100644
--- a/backend/app/api/endpoints/analysis.py
+++ b/backend/app/api/endpoints/analysis.py
@@ -18,6 +18,7 @@ from sqlalchemy.ext.asyncio import AsyncSession
 
 from app.core.database import get_db, AsyncSessionLocal
 from app.models.models import StrategyOptimizationLog, TradeJournal
+from app.core.timeutil import now_kst
 from app.services.trade_analyzer import (
     analyze_performance,
     build_insights,
@@ -71,7 +72,7 @@ async def get_insights(
             "performance_summary": perf.get("summary", {}),
             "last_optimization_date": last_opt_date.isoformat() if last_opt_date else None,
             "period_days": days,
-            "generated_at": datetime.utcnow().isoformat(),
+            "generated_at": now_kst().isoformat(),
         }
     except Exception as e:
         logger.error(f"insights 생성 실패: {e}", exc_info=True)
diff --git a/backend/app/api/endpoints/auth.py b/backend/app/api/endpoints/auth.py
index 7888fef..6000d08 100644
--- a/backend/app/api/endpoints/auth.py
+++ b/backend/app/api/endpoints/auth.py
@@ -42,6 +42,7 @@ from app.core.security import (
     verify_session_token,
 )
 from app.models.models import User
+from app.core.timeutil import now_kst
 
 logger = logging.getLogger(__name__)
 router = APIRouter()
@@ -246,7 +247,7 @@ async def login(body: LoginRequest, request: Request, db: AsyncSession = Depends
         )
 
     _failures.pop(ip, None)
-    user.last_login_at = datetime.utcnow()
+    user.last_login_at = now_kst()
     await db.commit()
 
     token, expires_at = create_session_token(user.username)
diff --git a/backend/app/api/endpoints/kis_credentials.py b/backend/app/api/endpoints/kis_credentials.py
index b99a032..6e6b9c9 100644
--- a/backend/app/api/endpoints/kis_credentials.py
+++ b/backend/app/api/endpoints/kis_credentials.py
@@ -27,6 +27,7 @@ from app.core.tenant_auth import CurrentUser, get_current_user
 from app.models.models import UserKisCredential
 from app.services.korea_investment_api import KoreaInvestmentAPI
 from app.services.tenant.registry import user_context_registry
+from app.core.timeutil import now_kst
 
 logger = logging.getLogger(__name__)
 router = APIRouter()
@@ -172,7 +173,7 @@ async def put_credentials(
     if dup.scalar_one_or_none() is not None:
         raise HTTPException(status_code=status.HTTP_409_CONFLICT, detail="이미 다른 사용자가 등록한 앱키입니다.")
 
-    now = datetime.utcnow()
+    now = now_kst()
     cred = await _get_own(db, user_id)
     is_new = cred is None
     if is_new:
@@ -278,7 +279,7 @@ async def verify_credentials(
         "stock_value": _pick_float(output2, ["scts_evlu_amt", "evlu_amt_smtl_amt"]),
     }
 
-    now = datetime.utcnow()
+    now = now_kst()
     cred.last_verified_at = now
     cred.is_enabled = True
     cred.updated_at = now
@@ -306,7 +307,7 @@ async def patch_auto_trade(
         )
 
     cred.auto_trade_enabled = body.enabled
-    cred.updated_at = datetime.utcnow()
+    cred.updated_at = now_kst()
     await db.commit()
     # H3: 캐시된 UserContext.auto_trade_enabled 스냅샷이 갱신되도록 무효화(다음 호출에서 재조립).
     await user_context_registry.invalidate(user_id)
diff --git a/backend/app/api/endpoints/portfolio.py b/backend/app/api/endpoints/portfolio.py
index 7da8f13..dd19a8c 100644
--- a/backend/app/api/endpoints/portfolio.py
+++ b/backend/app/api/endpoints/portfolio.py
@@ -29,6 +29,7 @@ from app.services.utils import _is_domestic
 import asyncio
 import logging
 from datetime import datetime, timedelta
+from app.core.timeutil import now_kst
 
 logger = logging.getLogger(__name__)
 
@@ -1428,7 +1429,7 @@ async def _create_journal_background(
             "trade_id": trade_id,
             "stock_code": stock_code,
             "stock_name": stock_name,
-            "journal_date": datetime.utcnow(),
+            "journal_date": now_kst(),
             "content": content,
             "strategy_name": "AUTO_TRADE",
             "mood": mood,
@@ -1699,7 +1700,7 @@ async def update_active_trade_status(
 
         # 상태 업데이트
         active_trade.status = new_status
-        active_trade.updated_at = datetime.fromisoformat(request.updated_at) if request.updated_at else datetime.utcnow()
+        active_trade.updated_at = datetime.fromisoformat(request.updated_at) if request.updated_at else now_kst()
 
         # 부분 매도 시 잔여 비율 갱신 (CLAUDE.md 5.2: +2R 50% 분할 매도 후 잔량 추적 유지)
         if request.remaining_pct is not None:
diff --git a/backend/app/api/endpoints/risk_management.py b/backend/app/api/endpoints/risk_management.py
index d4ad9f0..adcf1a2 100644
--- a/backend/app/api/endpoints/risk_management.py
+++ b/backend/app/api/endpoints/risk_management.py
@@ -28,6 +28,7 @@ def _today_kst() -> date:
 from app.core.config import settings
 from app.core.security import require_api_key
 from app.models.models import TradeHistory, TradingSession, Portfolio
+from app.core.timeutil import now_kst
 
 router = APIRouter()
 logger = logging.getLogger(__name__)
@@ -54,7 +55,7 @@ async def get_risk_metrics(
     - 현재 계좌 상태
     """
     try:
-        since_date = datetime.utcnow() - timedelta(days=days)
+        since_date = now_kst() - timedelta(days=days)
         
         # 매도 완료된 거래만 조회 (실현 손익)
         result = await db.execute(
@@ -149,7 +150,7 @@ async def get_sharpe_ratio(
     - < 1.0: 개선 필요
     """
     try:
-        since_date = datetime.utcnow() - timedelta(days=days)
+        since_date = now_kst() - timedelta(days=days)
         
         result = await db.execute(
             select(TradeHistory)
@@ -443,7 +444,7 @@ async def get_win_rate(
     📊 승률 및 손익 통계
     """
     try:
-        since_date = datetime.utcnow() - timedelta(days=days)
+        since_date = now_kst() - timedelta(days=days)
         
         result = await db.execute(
             select(TradeHistory)
diff --git a/backend/app/api/endpoints/trades.py b/backend/app/api/endpoints/trades.py
index 37396e9..9086652 100644
--- a/backend/app/api/endpoints/trades.py
+++ b/backend/app/api/endpoints/trades.py
@@ -17,6 +17,7 @@ import re
 from app.core.database import get_db
 from app.models.models import TradeHistory
 from pydantic import BaseModel
+from app.core.timeutil import now_kst
 
 router = APIRouter()
 logger = logging.getLogger(__name__)
@@ -62,7 +63,7 @@ async def get_trade_history(
     query = select(TradeHistory)
     
     # 날짜 필터
-    since_date = datetime.utcnow() - timedelta(days=days)
+    since_date = now_kst() - timedelta(days=days)
     query = query.where(TradeHistory.created_at >= since_date)
     
     # 종목 코드 필터
@@ -158,7 +159,7 @@ async def get_trade_stats(
     db: AsyncSession = Depends(get_db)
 ):
     """거래 통계 조회"""
-    since_date = datetime.utcnow() - timedelta(days=days)
+    since_date = now_kst() - timedelta(days=days)
     
     result = await db.execute(
         select(TradeHistory).where(TradeHistory.created_at >= since_date)
diff --git a/backend/app/api/endpoints/trades_v2.py b/backend/app/api/endpoints/trades_v2.py
index e89fec2..87f50e0 100644
--- a/backend/app/api/endpoints/trades_v2.py
+++ b/backend/app/api/endpoints/trades_v2.py
@@ -22,6 +22,7 @@ from app.core.tenant_auth import CurrentUser, get_current_user
 from app.models.models import TradeHistory
 from app.api.endpoints.portfolio_v2 import _resolve_target_user_id, _user_scope_filter
 from app.api.endpoints.trades import TradeHistoryResponse
+from app.core.timeutil import now_kst
 
 logger = logging.getLogger(__name__)
 router = APIRouter()
@@ -44,7 +45,7 @@ async def get_trade_history_v2(
 
     query = select(TradeHistory).where(_user_scope_filter(TradeHistory.user_id, target_user_id))
 
-    since_date = datetime.utcnow() - timedelta(days=days)
+    since_date = now_kst() - timedelta(days=days)
     query = query.where(TradeHistory.created_at >= since_date)
 
     if stock_code:
diff --git a/backend/app/api/endpoints/trading_rules.py b/backend/app/api/endpoints/trading_rules.py
index 92a7d1e..d3c0e9f 100644
--- a/backend/app/api/endpoints/trading_rules.py
+++ b/backend/app/api/endpoints/trading_rules.py
@@ -18,6 +18,7 @@ from app.core.database import get_db
 from app.core.security import require_api_key
 from app.models.models import TradingRule
 from pydantic import BaseModel
+from app.core.timeutil import now_kst
 
 router = APIRouter()
 
@@ -118,7 +119,7 @@ async def update_trading_rule(
     for field, value in update_data.items():
         setattr(db_rule, field, value)
     
-    db_rule.updated_at = datetime.utcnow()
+    db_rule.updated_at = now_kst()
     await db.commit()
     await db.refresh(db_rule)
     return db_rule
@@ -148,7 +149,7 @@ async def toggle_trading_rule(rule_id: int, db: AsyncSession = Depends(get_db)):
         raise HTTPException(status_code=404, detail="Trading rule not found")
     
     db_rule.is_active = not db_rule.is_active
-    db_rule.updated_at = datetime.utcnow()
+    db_rule.updated_at = now_kst()
     await db.commit()
     await db.refresh(db_rule)
     return db_rule
diff --git a/backend/app/core/timeutil.py b/backend/app/core/timeutil.py
new file mode 100644
index 0000000..5cfe625
--- /dev/null
+++ b/backend/app/core/timeutil.py
@@ -0,0 +1,26 @@
+"""timeutil — 애플리케이션 전역 시각 기준.
+
+[2026-09-23] DB 타임스탬프가 UTC/KST 로 섞여 있었다.
+  - 모델 기본값(`default=datetime.utcnow`)으로 저장된 행 → UTC
+  - `_get_kst_now()` 를 명시한 경로(수동 매매 등) → KST
+같은 테이블 안에서 9시간 차이가 나 화면의 매매 시각이 뒤죽박죽이었고,
+`now_kst()` 로 만든 조회 구간과 비교하는 로직도 9시간씩 어긋났다
+(예: 추가매수 쿨다운이 항상 발동).
+
+국내 증시만 다루고 모든 비교가 KST 거래일 기준이므로 **KST naive** 로 통일한다.
+"""
+from datetime import date, datetime
+
+import pytz
+
+KST = pytz.timezone("Asia/Seoul")
+
+
+def now_kst() -> datetime:
+    """현재 한국 시간 (timezone-naive) — DB 저장·비교의 유일한 기준."""
+    return datetime.now(KST).replace(tzinfo=None)
+
+
+def today_kst() -> date:
+    """오늘 날짜 (KST)."""
+    return now_kst().date()
diff --git a/backend/app/models/models.py b/backend/app/models/models.py
index d47df66..037b9e9 100644
--- a/backend/app/models/models.py
+++ b/backend/app/models/models.py
@@ -17,6 +17,7 @@ from typing import Optional, List
 from sqlalchemy import Column, Integer, BigInteger, String, Numeric, Boolean, DateTime, Text, ARRAY, Date, ForeignKey, UniqueConstraint
 from sqlalchemy.dialects.postgresql import JSONB
 from app.core.database import Base
+from app.core.timeutil import now_kst
 
 
 class StockDailyPrice(Base):
@@ -57,8 +58,8 @@ class TradingSession(Base):
     starting_balance = Column(Numeric(15, 2))
     ending_balance = Column(Numeric(15, 2))
     peak_balance = Column(Numeric(15, 2))
-    created_at = Column(DateTime, default=datetime.utcnow)
-    updated_at = Column(DateTime, default=datetime.utcnow, onupdate=datetime.utcnow)
+    created_at = Column(DateTime, default=now_kst)
+    updated_at = Column(DateTime, default=now_kst, onupdate=now_kst)
 
 
 class TradingRule(Base):
@@ -72,8 +73,8 @@ class TradingRule(Base):
     actions = Column(JSONB, nullable=False)
     is_active = Column(Boolean, default=True)
     priority = Column(Integer, default=0)
-    created_at = Column(DateTime, default=datetime.utcnow)
-    updated_at = Column(DateTime, default=datetime.utcnow, onupdate=datetime.utcnow)
+    created_at = Column(DateTime, default=now_kst)
+    updated_at = Column(DateTime, default=now_kst, onupdate=now_kst)
 
 
 class StrategyConfig(Base):
@@ -118,8 +119,8 @@ class StrategyConfig(Base):
     is_active = Column(Boolean, default=True, nullable=False)  # False면 기본값 사용
     updated_by = Column(String(100), nullable=True)  # 마지막 수정자
 
-    created_at = Column(DateTime, default=datetime.utcnow)
-    updated_at = Column(DateTime, default=datetime.utcnow, onupdate=datetime.utcnow)
+    created_at = Column(DateTime, default=now_kst)
+    updated_at = Column(DateTime, default=now_kst, onupdate=now_kst)
 
 
 class TradeHistory(Base):
@@ -153,7 +154,7 @@ class TradeHistory(Base):
     currency_code = Column(String(3), nullable=False, default="KRW")
     exchange_code = Column(String(10), nullable=True)
     fx_rate = Column(Numeric(10, 4), nullable=True)  # 체결 시점 환율
-    created_at = Column(DateTime, default=datetime.utcnow, index=True)
+    created_at = Column(DateTime, default=now_kst, index=True)
     executed_at = Column(DateTime)
 
 
@@ -175,7 +176,7 @@ class Portfolio(Base):
     strategy_type = Column(String(20), nullable=False, default="swing", index=True)
     currency_code = Column(String(3), nullable=False, default="KRW")
     exchange_code = Column(String(10), nullable=True)  # NASD, NYSE, AMEX, KRX
-    updated_at = Column(DateTime, default=datetime.utcnow, onupdate=datetime.utcnow)
+    updated_at = Column(DateTime, default=now_kst, onupdate=now_kst)
 
 
 class MarketData(Base):
@@ -189,7 +190,7 @@ class MarketData(Base):
     high_price = Column(Numeric(15, 2))
     low_price = Column(Numeric(15, 2))
     open_price = Column(Numeric(15, 2))
-    timestamp = Column(DateTime, default=datetime.utcnow, index=True)
+    timestamp = Column(DateTime, default=now_kst, index=True)
 
 
 class News(Base):
@@ -204,7 +205,7 @@ class News(Base):
     sentiment = Column(String(20))  # positive / negative / neutral
     sentiment_score = Column(Numeric(5, 3), nullable=True)  # -1.000 ~ +1.000
     published_at = Column(DateTime, index=True)
-    created_at = Column(DateTime, default=datetime.utcnow)
+    created_at = Column(DateTime, default=now_kst)
 
 
 class ClaudeAnalysisLog(Base):
@@ -219,7 +220,7 @@ class ClaudeAnalysisLog(Base):
     analysis_result = Column(JSONB)
     decision = Column(String(50))
     confidence = Column(Numeric(5, 4))
-    created_at = Column(DateTime, default=datetime.utcnow, index=True)
+    created_at = Column(DateTime, default=now_kst, index=True)
 
 
 class MCPToolCall(Base):
@@ -232,7 +233,7 @@ class MCPToolCall(Base):
     result = Column(JSONB)
     status = Column(String(50))
     execution_time_ms = Column(Integer)
-    created_at = Column(DateTime, default=datetime.utcnow, index=True)
+    created_at = Column(DateTime, default=now_kst, index=True)
 
 
 class StockAnalysis(Base):
@@ -265,8 +266,8 @@ class StockAnalysis(Base):
     ml_score = Column(Integer, nullable=True)
     ml_confidence = Column(Numeric(5, 4), nullable=True)
     ml_signal = Column(String(10), nullable=True)
-    created_at = Column(DateTime, default=datetime.utcnow)
-    updated_at = Column(DateTime, default=datetime.utcnow, onupdate=datetime.utcnow)
+    created_at = Column(DateTime, default=now_kst)
+    updated_at = Column(DateTime, default=now_kst, onupdate=now_kst)
 
 
 class ActiveTrade(Base):
@@ -293,8 +294,8 @@ class ActiveTrade(Base):
     strategy_name = Column(String(100), nullable=True)
     currency_code = Column(String(3), nullable=False, default="KRW")
     exchange_code = Column(String(10), nullable=True)  # NASD, NYSE, AMEX, KRX
-    created_at = Column(DateTime, default=datetime.utcnow)
-    updated_at = Column(DateTime, default=datetime.utcnow, onupdate=datetime.utcnow)
+    created_at = Column(DateTime, default=now_kst)
+    updated_at = Column(DateTime, default=now_kst, onupdate=now_kst)
 
 
 class ExchangeRate(Base):
@@ -305,7 +306,7 @@ class ExchangeRate(Base):
     currency_pair = Column(String(7), nullable=False, index=True)  # USD/KRW
     rate = Column(Numeric(12, 4), nullable=False)
     source = Column(String(50), default="KIS")
-    recorded_at = Column(DateTime, default=datetime.utcnow, index=True)
+    recorded_at = Column(DateTime, default=now_kst, index=True)
 
 
 class UsStockUniverse(Base):
@@ -322,7 +323,7 @@ class UsStockUniverse(Base):
     sector = Column(String(100), nullable=True)
     market_cap = Column(BigInteger, nullable=True)
     is_active = Column(Boolean, default=True, index=True)
-    updated_at = Column(DateTime, default=datetime.utcnow, onupdate=datetime.utcnow)
+    updated_at = Column(DateTime, default=now_kst, onupdate=now_kst)
 
 
 class TradeJournal(Base):
@@ -333,14 +334,14 @@ class TradeJournal(Base):
     trade_id = Column(Integer)
     stock_code = Column(String(20), nullable=False, index=True)
     stock_name = Column(String(100))
-    journal_date = Column(DateTime, default=datetime.utcnow)
+    journal_date = Column(DateTime, default=now_kst)
     content = Column(Text)
     strategy_name = Column(String(100))
     mood = Column(String(50))
     tags = Column(JSONB)
     screenshot_url = Column(Text)
-    created_at = Column(DateTime, default=datetime.utcnow)
-    updated_at = Column(DateTime, default=datetime.utcnow, onupdate=datetime.utcnow)
+    created_at = Column(DateTime, default=now_kst)
+    updated_at = Column(DateTime, default=now_kst, onupdate=now_kst)
 
 
 class StockBan(Base):
@@ -351,7 +352,7 @@ class StockBan(Base):
     stock_code = Column(String(20), primary_key=True)
     consecutive_losses = Column(Integer, default=0, nullable=False)
     ban_until = Column(DateTime, nullable=True)
-    updated_at = Column(DateTime, default=datetime.utcnow, onupdate=datetime.utcnow)
+    updated_at = Column(DateTime, default=now_kst, onupdate=now_kst)
 
 
 class StockBanV2(Base):
@@ -371,7 +372,7 @@ class StockBanV2(Base):
     stock_code = Column(String(20), nullable=False, index=True)
     consecutive_losses = Column(Integer, default=0, nullable=False)
     ban_until = Column(DateTime, nullable=True)
-    updated_at = Column(DateTime, default=datetime.utcnow, onupdate=datetime.utcnow)
+    updated_at = Column(DateTime, default=now_kst, onupdate=now_kst)
 
 
 class WatchlistStock(Base):
@@ -419,7 +420,7 @@ class StrategyOptimizationLog(Base):
     applied = Column(Boolean, default=False, nullable=False)
     apply_reason = Column(Text, nullable=True)
     total_combinations = Column(Integer, nullable=True)
-    created_at = Column(DateTime, default=datetime.utcnow, index=True)
+    created_at = Column(DateTime, default=now_kst, index=True)
 
 
 class User(Base):
@@ -436,7 +437,7 @@ class User(Base):
     password_hash = Column(String(128), nullable=False)
     is_active = Column(Boolean, default=False, nullable=False)
     is_admin = Column(Boolean, default=False, nullable=False)
-    created_at = Column(DateTime, default=datetime.utcnow, nullable=False)
+    created_at = Column(DateTime, default=now_kst, nullable=False)
     last_login_at = Column(DateTime, nullable=True)
 
 
@@ -462,5 +463,5 @@ class UserKisCredential(Base):
     auto_trade_enabled = Column(Boolean, default=False, nullable=False)
     last_verified_at = Column(DateTime, nullable=True)
     key_version = Column(Integer, default=1, nullable=False)  # 암호화 키 로테이션용
-    created_at = Column(DateTime, default=datetime.utcnow, nullable=False)
-    updated_at = Column(DateTime, default=datetime.utcnow, onupdate=datetime.utcnow)
+    created_at = Column(DateTime, default=now_kst, nullable=False)
+    updated_at = Column(DateTime, default=now_kst, onupdate=now_kst)
diff --git a/backend/app/services/db_worker.py b/backend/app/services/db_worker.py
index 5c0de52..00447d9 100644
--- a/backend/app/services/db_worker.py
+++ b/backend/app/services/db_worker.py
@@ -38,6 +38,7 @@ from sqlalchemy import select
 
 from app.core.database import AsyncSessionLocal
 from app.models.models import TradeHistory
+from app.core.timeutil import now_kst
 
 logger = logging.getLogger(__name__)
 
@@ -291,7 +292,7 @@ async def enqueue_trade_journal(trade, content: str) -> None:
             "trade_id": trade.id,
             "stock_code": trade.stock_code,
             "stock_name": trade.stock_name,
-            "journal_date": trade.executed_at or trade.created_at or datetime.utcnow(),
+            "journal_date": trade.executed_at or trade.created_at or now_kst(),
             "content": content,
             "strategy_name": strategy,
             "mood": mood,
@@ -450,7 +451,7 @@ async def db_writer_worker() -> None:
                         set_={
                             "consecutive_losses": stmt.excluded.consecutive_losses,
                             "ban_until": stmt.excluded.ban_until,
-                            "updated_at": datetime.utcnow(),
+                            "updated_at": now_kst(),
                         },
                     )
                     await session.execute(stmt)
@@ -612,7 +613,7 @@ async def db_writer_worker() -> None:
 
                     if record:
                         record.status = "closed"
-                        record.updated_at = _dt.utcnow()
+                        record.updated_at = now_kst()
                         await session.commit()
                         logger.debug(
                             "✅ [Worker] ActiveTrade closed: %s (strategy=%s)",
diff --git a/backend/app/services/ml_retrain_pipeline.py b/backend/app/services/ml_retrain_pipeline.py
index ebcd2a8..37dcb9b 100644
--- a/backend/app/services/ml_retrain_pipeline.py
+++ b/backend/app/services/ml_retrain_pipeline.py
@@ -33,6 +33,7 @@ import pytz
 
 from app.core.config import settings
 from app.core.database import AsyncSessionLocal
+from app.core.timeutil import now_kst
 from app.services.feature_engineering import (
     extract_features,
     db_data_to_dataframe,
@@ -397,11 +398,11 @@ async def _load_trade_history(
     from sqlalchemy import select, and_
     from app.models.models import TradeHistory
 
-    # [FIX] TradeHistory.created_at은 timestamp WITHOUT time zone(naive UTC, datetime.utcnow
+    # [2026-09-23] TradeHistory.created_at 은 KST naive (app.core.timeutil.now_kst)
     # 저장)이므로, tz-aware인 datetime.now(KST)로 비교하면 asyncpg가
     # "can't subtract offset-naive and offset-aware datetimes" DataError를 낸다.
     # 컬럼과 동일하게 naive UTC로 맞춘다.
-    cutoff = datetime.utcnow() - timedelta(days=months * 30)
+    cutoff = now_kst() - timedelta(days=months * 30)
 
     async with AsyncSessionLocal() as session:
         stmt = (
diff --git a/backend/app/services/news_sentiment.py b/backend/app/services/news_sentiment.py
index 2826c0d..ac91d98 100644
--- a/backend/app/services/news_sentiment.py
+++ b/backend/app/services/news_sentiment.py
@@ -24,6 +24,7 @@ from bs4 import BeautifulSoup
 from app.core.config import settings
 from app.core.redis import setex_json, get_json
 from app.services.db_worker import db_task_queue
+from app.core.timeutil import now_kst
 
 logger = logging.getLogger(__name__)
 
@@ -168,7 +169,7 @@ def _compute_aggregate_score(articles: List[Dict[str, Any]]) -> float:
     if not articles:
         return 0.0
 
-    now = datetime.utcnow()
+    now = now_kst()
     weighted_sum = 0.0
     weight_total = 0.0
 
@@ -327,7 +328,7 @@ async def collect_market_news(limit: int = 0) -> List[Dict[str, Any]]:
                     "stock_codes": [],  # 시장 뉴스는 특정 종목 없음
                     "sentiment": label,
                     "sentiment_score": score,
-                    "published_at": datetime.utcnow(),  # 파싱 불가 시 현재 시간
+                    "published_at": now_kst(),  # 파싱 불가 시 현재 시간
                 })
 
                 if len(articles) >= limit:
@@ -392,7 +393,7 @@ async def collect_newsapi_news(
             try:
                 published_at = datetime.fromisoformat(pub_str.replace("Z", "+00:00"))
             except Exception:
-                published_at = datetime.utcnow()
+                published_at = now_kst()
 
             score, label = analyze_sentiment_keyword(title, content)
 
@@ -567,7 +568,7 @@ def _parse_naver_date(date_str: str) -> datetime:
     형식: "2026.03.24 09:15" 또는 "2026.03.24"
     """
     if not date_str:
-        return datetime.utcnow()
+        return now_kst()
 
     date_str = date_str.strip()
     for fmt in ("%Y.%m.%d %H:%M", "%Y.%m.%d"):
@@ -576,7 +577,7 @@ def _parse_naver_date(date_str: str) -> datetime:
         except ValueError:
             continue
 
-    return datetime.utcnow()
+    return now_kst()
 
 
 # ═════════════════════════════════════════════════════════════════════════════
diff --git a/backend/app/services/schedulers.py b/backend/app/services/schedulers.py
index edcbcff..f13ef38 100644
--- a/backend/app/services/schedulers.py
+++ b/backend/app/services/schedulers.py
@@ -13,6 +13,7 @@ from datetime import datetime as _dt, date as _date, timedelta as _td
 
 from app.core.config import settings
 from app.core.database import AsyncSessionLocal
+from app.core.timeutil import now_kst
 from app.core.market_schedule import (
     is_market_open, seconds_until_market_open, is_pre_market_window,
 )
@@ -224,7 +225,6 @@ async def post_market_analyzer_scheduler():
                 )
                 from app.models.models import TradeHistory
                 from sqlalchemy import select, func, and_
-                from datetime import datetime as _utcnow_dt
 
                 async with AsyncSessionLocal() as db:
                     uncovered = await get_uncovered_trades(db, days=7)
@@ -246,7 +246,7 @@ async def post_market_analyzer_scheduler():
                     try:
                         from app.services.telegram_notifier import telegram_notifier
                         # 당일 SELL 체결 내역으로 PnL 계산
-                        _today_start = _utcnow_dt.utcnow().replace(hour=0, minute=0, second=0, microsecond=0)
+                        _today_start = now_kst().replace(hour=0, minute=0, second=0, microsecond=0)
                         _today_sells = await db.execute(
                             select(TradeHistory).where(
                                 and_(
@@ -282,7 +282,7 @@ async def post_market_analyzer_scheduler():
                     except Exception as _tg_err:
                         logger.debug(f"[PostMarket] Telegram 리포트 전송 실패: {_tg_err}")
 
-                    since_7d = _utcnow_dt.utcnow() - _td(days=7)
+                    since_7d = now_kst() - _td(days=7)
                     trade_count_result = await db.execute(
                         select(func.count(TradeHistory.id)).where(
                             and_(
diff --git a/backend/app/services/stock_pattern_memory.py b/backend/app/services/stock_pattern_memory.py
index f7e4013..3cdf357 100644
--- a/backend/app/services/stock_pattern_memory.py
+++ b/backend/app/services/stock_pattern_memory.py
@@ -27,6 +27,7 @@ from datetime import datetime, date, timedelta
 from typing import Optional, List, Dict, Tuple
 
 from app.core.config import settings
+from app.core.timeutil import now_kst
 
 logger = logging.getLogger(__name__)
 
@@ -791,7 +792,7 @@ async def build_stock_profile(stock_code: str) -> Optional[StockProfile]:
         total_trades=trade_stats["total_trades"],
         beta=beta,
         sector="",  # 별도 섹터 DB 필요 시 확장
-        last_updated=datetime.utcnow().isoformat(),
+        last_updated=now_kst().isoformat(),
     )
     return profile
 
@@ -899,7 +900,7 @@ async def refresh_all_profiles_with_percentile(stock_codes: List[str]) -> int:
         # 해당 종목의 순위 → 백분위
         rank = sorted_ranges.index(p.avg_daily_range_pct)
         p.volatility_percentile = round(rank / n * 100, 1) if n > 1 else 50.0
-        p.last_updated = datetime.utcnow().isoformat()
+        p.last_updated = now_kst().isoformat()
 
     # 3단계: 캐시 저장
     success = 0
diff --git a/backend/app/services/strategy_config_service.py b/backend/app/services/strategy_config_service.py
index b2b55b4..45e48b6 100644
--- a/backend/app/services/strategy_config_service.py
+++ b/backend/app/services/strategy_config_service.py
@@ -29,6 +29,7 @@ from sqlalchemy.dialects.postgresql import insert as pg_insert
 
 from app.core.database import AsyncSessionLocal
 from app.models.models import StrategyConfig
+from app.core.timeutil import now_kst
 
 logger = logging.getLogger(__name__)
 
@@ -219,7 +220,7 @@ class StrategyConfigService:
 
                 cfg.value = value
                 cfg.updated_by = updated_by
-                cfg.updated_at = __import__("datetime").datetime.utcnow()
+                cfg.updated_at = __import__("datetime").now_kst()
                 await session.commit()
                 await session.refresh(cfg)
 
diff --git a/backend/app/services/strategy_optimizer.py b/backend/app/services/strategy_optimizer.py
index 5373706..90e480f 100644
--- a/backend/app/services/strategy_optimizer.py
+++ b/backend/app/services/strategy_optimizer.py
@@ -27,6 +27,7 @@ from app.core.database import AsyncSessionLocal
 from app.models.models import StrategyOptimizationLog, StockDailyPrice
 from app.services.strategy_config_service import strategy_cfg
 from app.services.backtest_engine import BacktestEngine, BacktestConfig
+from app.core.timeutil import now_kst
 
 logger = logging.getLogger(__name__)
 
@@ -193,7 +194,7 @@ async def _get_representative_stocks(period_days: int = 90) -> List[str]:
     from sqlalchemy import func, and_
     from datetime import datetime, timedelta
 
-    since = datetime.utcnow() - timedelta(days=period_days)
+    since = now_kst() - timedelta(days=period_days)
 
     async with AsyncSessionLocal() as db:
         stmt = (
diff --git a/backend/app/services/trade_analyzer.py b/backend/app/services/trade_analyzer.py
index c8b3e04..4816831 100644
--- a/backend/app/services/trade_analyzer.py
+++ b/backend/app/services/trade_analyzer.py
@@ -20,6 +20,7 @@ from sqlalchemy import select, and_, func
 from sqlalchemy.ext.asyncio import AsyncSession
 
 from app.models.models import TradeHistory, TradeJournal
+from app.core.timeutil import now_kst
 
 logger = logging.getLogger(__name__)
 
@@ -380,7 +381,7 @@ async def analyze_performance(db: AsyncSession, days: int = 30) -> Dict[str, Any
           "generated_at": ISO 문자열
         }
     """
-    since = datetime.utcnow() - timedelta(days=days)
+    since = now_kst() - timedelta(days=days)
 
     stmt = select(TradeHistory).where(
         and_(
@@ -408,7 +409,7 @@ async def analyze_performance(db: AsyncSession, days: int = 30) -> Dict[str, Any
             "drift_alerts": [],
             "period_days": days,
             "total_trades": 0,
-            "generated_at": datetime.utcnow().isoformat(),
+            "generated_at": now_kst().isoformat(),
         }
 
     # ── 전체 통계 ──────────────────────────────────────────────────────────
@@ -526,7 +527,7 @@ async def analyze_performance(db: AsyncSession, days: int = 30) -> Dict[str, Any
         "drift_alerts": drift_alerts,
         "period_days": days,
         "total_trades": len(trades),
-        "generated_at": datetime.utcnow().isoformat(),
+        "generated_at": now_kst().isoformat(),
     }
 
 
@@ -637,7 +638,7 @@ def build_insights(perf: Dict[str, Any]) -> List[Dict[str, str]]:
 
 async def get_uncovered_trades(db: AsyncSession, days: int = 7) -> List[TradeHistory]:
     """일지가 아직 없는 완료 SELL 거래 목록을 반환."""
-    since = datetime.utcnow() - timedelta(days=days)
+    since = now_kst() - timedelta(days=days)
 
     # 이미 일지가 있는 trade_id 목록
     covered_stmt = select(TradeJournal.trade_id).where(TradeJournal.trade_id.is_not(None))
@@ -753,7 +754,7 @@ async def create_journal_record(
         trade_id=trade.id,
         stock_code=trade.stock_code,
         stock_name=trade.stock_name,
-        journal_date=trade.executed_at or trade.created_at or datetime.utcnow(),
+        journal_date=trade.executed_at or trade.created_at or now_kst(),
         content=content,
         strategy_name=strategy,
         mood=mood,
diff --git a/backend/app/services/trade_executor.py b/backend/app/services/trade_executor.py
index 5de2b6d..4209226 100644
--- a/backend/app/services/trade_executor.py
+++ b/backend/app/services/trade_executor.py
@@ -32,6 +32,7 @@ from app.services.technical_indicators import (
 from app.services.signal_types import BUY_KEYWORDS, SELL_KEYWORDS, STRONG_BUY_KEYWORDS, BLOCK_KEYWORDS
 from app.services.correlation_filter import validate_correlation_filter
 from app.services.exchange_detector import is_us_stock, detect_exchange, get_market_info
+from app.core.timeutil import now_kst
 from app.services.trade_helpers import (
     check_opening_range_volatility, check_surge_prevention, check_trend_filter,
     calculate_cooldown_minutes, get_daily_cutoff_utc, get_leverage_check_keywords,
@@ -725,7 +726,7 @@ async def _execute_buy(
         if available_cash > 0:
             _set_account_cache(available_cash, total_assets)
 
-    # [이슈1 수정] TradeHistory.created_at은 UTC 저장(datetime.utcnow)이므로
+    # [2026-09-23] TradeHistory.created_at 은 KST 저장(now_kst)이므로
     # daily_cutoff도 UTC 기준으로 계산해야 9시간 오차가 없음.
     daily_cutoff = get_daily_cutoff_utc()  # 오늘 00:00:00 UTC
 
@@ -770,9 +771,9 @@ async def _execute_buy(
     )
     recent_buys = cooldown_check.scalars().all()
     # 마지막 매수 이후 쿨다운 시간이 지나지 않았으면 HOLD
-    # [이슈1 수정] created_at은 UTC이므로 현재 시각도 UTC로 비교
-    from datetime import datetime as _dt_utc2
-    if recent_buys and (_dt_utc2.utcnow() - recent_buys[0].created_at).total_seconds() < cooldown_min * 60:
+    # created_at·현재시각 모두 KST naive 기준 (예전에는 UTC now 와 KST created_at 을
+    # 비교해 차이가 음수가 되어 쿨다운이 항상 발동했다)
+    if recent_buys and (now_kst() - recent_buys[0].created_at).total_seconds() < cooldown_min * 60:
         return {"action": "HOLD", "stock": stock_name, "reason": "cooldown"}
 
     # ── 6.5. 상관관계 필터 (CLAUDE.md 섹션 5.4) ──────────────────────────────────
diff --git a/backend/app/services/trade_helpers.py b/backend/app/services/trade_helpers.py
index 489a110..976d73a 100644
--- a/backend/app/services/trade_helpers.py
+++ b/backend/app/services/trade_helpers.py
@@ -19,6 +19,7 @@ from app.services.technical_indicators import (
 from app.core.market_schedule import is_opening_range_period
 from app.services.market_analyzer import _get_kst_now
 from app.services.exchange_detector import get_market_info
+from app.core.timeutil import now_kst
 
 logger = logging.getLogger(__name__)
 
@@ -214,7 +215,7 @@ def get_daily_cutoff_utc() -> _dt_utc:
     Returns:
         datetime: Today's 00:00:00 UTC
     """
-    return _dt_utc.utcnow().replace(hour=0, minute=0, second=0, microsecond=0)
+    return now_kst().replace(hour=0, minute=0, second=0, microsecond=0)
 
 
 def get_leverage_check_keywords() -> set:
diff --git a/backend/tests/test_timezone_consistency.py b/backend/tests/test_timezone_consistency.py
new file mode 100644
index 0000000..ec30d40
--- /dev/null
+++ b/backend/tests/test_timezone_consistency.py
@@ -0,0 +1,61 @@
+"""DB 타임스탬프 KST 통일 검증.
+
+2026-09-23: 모델 기본값은 datetime.utcnow(UTC), 일부 경로는 _get_kst_now(KST)로 저장해
+같은 테이블 안에서 9시간이 섞였다(화면 매매 시각이 02:14 처럼 표시). 조회 구간도
+utcnow 기준이라 비교가 9시간 어긋났다(추가매수 쿨다운 상시 발동).
+"""
+import inspect
+import pathlib
+from datetime import datetime, timedelta
+
+import pytz
+
+from app.core.timeutil import KST, now_kst, today_kst
+from app.models.models import ActiveTrade, Portfolio, TradeHistory
+
+
+def test_now_kst_is_naive_korean_time():
+    v = now_kst()
+    assert v.tzinfo is None
+    real = datetime.now(pytz.timezone("Asia/Seoul")).replace(tzinfo=None)
+    assert abs((real - v).total_seconds()) < 5
+    assert today_kst() == real.date()
+
+
+def test_now_kst_differs_from_utc_by_nine_hours():
+    delta = now_kst() - datetime.utcnow()
+    assert 8.9 * 3600 < delta.total_seconds() < 9.1 * 3600
+
+
+def test_model_defaults_use_kst():
+    for model, cols in [
+        (TradeHistory, ["created_at"]),
+        (ActiveTrade, ["created_at", "updated_at"]),
+        (Portfolio, ["updated_at"]),
+    ]:
+        for col in cols:
+            default = model.__table__.columns[col].default
+            assert default is not None, f"{model.__name__}.{col} 기본값 없음"
+            assert getattr(default.arg, "__name__", "") == "now_kst", (
+                f"{model.__name__}.{col} 이 KST 기준이 아님"
+            )
+
+
+def test_no_utcnow_left_in_app_code():
+    """app/ 전체에서 utcnow() 호출이 남아 있으면 다시 섞인다."""
+    root = pathlib.Path(__file__).resolve().parents[1] / "app"
+    offenders = []
+    for f in root.rglob("*.py"):
+        for i, line in enumerate(f.read_text().splitlines(), 1):
+            code = line.split("#", 1)[0]
+            if "utcnow()" in code:
+                offenders.append(f"{f.relative_to(root)}:{i}")
+    assert not offenders, f"utcnow() 잔존: {offenders}"
+
+
+def test_cooldown_compares_same_basis():
+    from app.services import trade_executor as te
+    src = inspect.getsource(te)
+    i = src.index("recent_buys[0].created_at")
+    window = src[max(0, i - 300): i + 100]
+    assert "now_kst()" in window, "쿨다운 비교가 KST 기준이 아님"
diff --git a/docker-compose.yml b/docker-compose.yml
index 1703933..9fe230f 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -114,6 +114,9 @@ services:
       - "127.0.0.1:8000:8000"
     volumes:
       - ./logs:/logs
+      # KIS 액세스 토큰 캐시 — 컨테이너 재생성 때마다 사라지면 매 배포마다 토큰을 새로
+      # 발급받게 되고, KIS가 잦은 재발급을 거부한다(EGW00103 "유효하지 않은 AppKey").
+      - ./token_cache:/root/.cache/auto-stock
     networks:
       - autostock-network
     depends_on: