diff --git a/backend/app/schemas/backtest.py b/backend/app/schemas/backtest.py
index 546b217..6d057d4 100644
--- a/backend/app/schemas/backtest.py
+++ b/backend/app/schemas/backtest.py
@@ -8,6 +8,8 @@ from enum import Enum
 
 from pydantic import BaseModel, Field
 
+from app.schemas.portfolio import FloatDecimal
+
 
 class RebalancePeriod(str, Enum):
     MONTHLY = "monthly"
@@ -39,13 +41,13 @@ class BacktestCreate(BaseModel):
 
 class BacktestMetrics(BaseModel):
     """Backtest result metrics."""
-    total_return: Decimal
-    cagr: Decimal
-    mdd: Decimal
-    sharpe_ratio: Decimal
-    volatility: Decimal
-    benchmark_return: Decimal
-    excess_return: Decimal
+    total_return: FloatDecimal
+    cagr: FloatDecimal
+    mdd: FloatDecimal
+    sharpe_ratio: FloatDecimal
+    volatility: FloatDecimal
+    benchmark_return: FloatDecimal
+    excess_return: FloatDecimal
 
 
 class BacktestResponse(BaseModel):
@@ -57,9 +59,9 @@ class BacktestResponse(BaseModel):
     start_date: date
     end_date: date
     rebalance_period: str
-    initial_capital: Decimal
-    commission_rate: Decimal
-    slippage_rate: Decimal
+    initial_capital: FloatDecimal
+    commission_rate: FloatDecimal
+    slippage_rate: FloatDecimal
     benchmark: str
     status: str
     created_at: datetime
@@ -80,9 +82,9 @@ class BacktestListItem(BaseModel):
     rebalance_period: str
     status: str
     created_at: datetime
-    total_return: Optional[Decimal] = None
-    cagr: Optional[Decimal] = None
-    mdd: Optional[Decimal] = None
+    total_return: Optional[FloatDecimal] = None
+    cagr: Optional[FloatDecimal] = None
+    mdd: Optional[FloatDecimal] = None
 
     class Config:
         from_attributes = True
@@ -91,9 +93,9 @@ class BacktestListItem(BaseModel):
 class EquityCurvePoint(BaseModel):
     """Single point in equity curve."""
     date: date
-    portfolio_value: Decimal
-    benchmark_value: Decimal
-    drawdown: Decimal
+    portfolio_value: FloatDecimal
+    benchmark_value: FloatDecimal
+    drawdown: FloatDecimal
 
     class Config:
         from_attributes = True
@@ -103,9 +105,9 @@ class HoldingItem(BaseModel):
     """Single holding at a rebalance date."""
     ticker: str
     name: str
-    weight: Decimal
+    weight: FloatDecimal
     shares: int
-    price: Decimal
+    price: FloatDecimal
 
 
 class RebalanceHoldings(BaseModel):
@@ -121,8 +123,8 @@ class TransactionItem(BaseModel):
     ticker: str
     action: str
     shares: int
-    price: Decimal
-    commission: Decimal
+    price: FloatDecimal
+    commission: FloatDecimal
 
     class Config:
         from_attributes = True
diff --git a/backend/app/schemas/portfolio.py b/backend/app/schemas/portfolio.py
index 5ae8eb4..0762dce 100644
--- a/backend/app/schemas/portfolio.py
+++ b/backend/app/schemas/portfolio.py
@@ -3,15 +3,21 @@ Portfolio related Pydantic schemas.
 """
 from datetime import datetime, date
 from decimal import Decimal
-from typing import Optional, List
+from typing import Annotated, Optional, List
 
-from pydantic import BaseModel, Field
+from pydantic import BaseModel, Field, PlainSerializer
+
+# Decimal type that serializes as float in JSON responses (not string)
+FloatDecimal = Annotated[
+    Decimal,
+    PlainSerializer(lambda v: float(v), return_type=float, when_used='json'),
+]
 
 
 # Target schemas
 class TargetBase(BaseModel):
     ticker: str
-    target_ratio: Decimal = Field(..., ge=0, le=100)
+    target_ratio: FloatDecimal = Field(..., ge=0, le=100)
 
 
 class TargetCreate(TargetBase):
@@ -27,7 +33,7 @@ class TargetResponse(TargetBase):
 class HoldingBase(BaseModel):
     ticker: str
     quantity: int = Field(..., ge=0)
-    avg_price: Decimal = Field(..., ge=0)
+    avg_price: FloatDecimal = Field(..., ge=0)
 
 
 class HoldingCreate(HoldingBase):
@@ -41,11 +47,11 @@ class HoldingResponse(HoldingBase):
 
 class HoldingWithValue(HoldingResponse):
     """Holding with calculated values."""
-    current_price: Decimal | None = None
-    value: Decimal | None = None
-    current_ratio: Decimal | None = None
-    profit_loss: Decimal | None = None
-    profit_loss_ratio: Decimal | None = None
+    current_price: FloatDecimal | None = None
+    value: FloatDecimal | None = None
+    current_ratio: FloatDecimal | None = None
+    profit_loss: FloatDecimal | None = None
+    profit_loss_ratio: FloatDecimal | None = None
 
 
 # Transaction schemas
@@ -53,7 +59,7 @@ class TransactionBase(BaseModel):
     ticker: str
     tx_type: str  # "buy" or "sell"
     quantity: int = Field(..., gt=0)
-    price: Decimal = Field(..., gt=0)
+    price: FloatDecimal = Field(..., gt=0)
     executed_at: datetime
     memo: Optional[str] = None
 
@@ -98,18 +104,18 @@ class PortfolioDetail(PortfolioResponse):
     """Portfolio with targets and holdings."""
     targets: List[TargetResponse] = []
     holdings: List[HoldingWithValue] = []
-    total_value: Decimal | None = None
-    total_invested: Decimal | None = None
-    total_profit_loss: Decimal | None = None
+    total_value: FloatDecimal | None = None
+    total_invested: FloatDecimal | None = None
+    total_profit_loss: FloatDecimal | None = None
 
 
 # Snapshot schemas
 class SnapshotHoldingResponse(BaseModel):
     ticker: str
     quantity: int
-    price: Decimal
-    value: Decimal
-    current_ratio: Decimal
+    price: FloatDecimal
+    value: FloatDecimal
+    current_ratio: FloatDecimal
 
     class Config:
         from_attributes = True
@@ -119,7 +125,7 @@ class SnapshotListItem(BaseModel):
     """Snapshot list item (without holdings)."""
     id: int
     portfolio_id: int
-    total_value: Decimal
+    total_value: FloatDecimal
     snapshot_date: date
 
     class Config:
@@ -130,7 +136,7 @@ class SnapshotResponse(BaseModel):
     """Snapshot detail with holdings."""
     id: int
     portfolio_id: int
-    total_value: Decimal
+    total_value: FloatDecimal
     snapshot_date: date
     holdings: List[SnapshotHoldingResponse] = []
 
@@ -141,9 +147,9 @@ class SnapshotResponse(BaseModel):
 class ReturnDataPoint(BaseModel):
     """Single data point for returns chart."""
     date: date
-    total_value: Decimal
-    daily_return: Decimal | None = None
-    cumulative_return: Decimal | None = None
+    total_value: FloatDecimal
+    daily_return: FloatDecimal | None = None
+    cumulative_return: FloatDecimal | None = None
 
 
 class ReturnsResponse(BaseModel):
@@ -151,8 +157,8 @@ class ReturnsResponse(BaseModel):
     portfolio_id: int
     start_date: date | None = None
     end_date: date | None = None
-    total_return: Decimal | None = None
-    cagr: Decimal | None = None
+    total_return: FloatDecimal | None = None
+    cagr: FloatDecimal | None = None
     data: List[ReturnDataPoint] = []
 
 
@@ -160,19 +166,19 @@ class ReturnsResponse(BaseModel):
 class RebalanceItem(BaseModel):
     ticker: str
     name: str | None = None
-    target_ratio: Decimal
-    current_ratio: Decimal
+    target_ratio: FloatDecimal
+    current_ratio: FloatDecimal
     current_quantity: int
-    current_value: Decimal
-    target_value: Decimal
-    diff_value: Decimal
+    current_value: FloatDecimal
+    target_value: FloatDecimal
+    diff_value: FloatDecimal
     diff_quantity: int
     action: str  # "buy", "sell", or "hold"
 
 
 class RebalanceResponse(BaseModel):
     portfolio_id: int
-    total_value: Decimal
+    total_value: FloatDecimal
     items: List[RebalanceItem]
 
 
@@ -182,9 +188,9 @@ class RebalanceSimulationRequest(BaseModel):
 
 class RebalanceSimulationResponse(BaseModel):
     portfolio_id: int
-    current_total: Decimal
-    additional_amount: Decimal
-    new_total: Decimal
+    current_total: FloatDecimal
+    additional_amount: FloatDecimal
+    new_total: FloatDecimal
     items: List[RebalanceItem]
 
 
@@ -199,22 +205,22 @@ class RebalanceCalculateItem(BaseModel):
     """Extended rebalance item with price change info."""
     ticker: str
     name: str | None = None
-    target_ratio: Decimal
-    current_ratio: Decimal
+    target_ratio: FloatDecimal
+    current_ratio: FloatDecimal
     current_quantity: int
-    current_value: Decimal
-    current_price: Decimal
-    target_value: Decimal
-    diff_ratio: Decimal
+    current_value: FloatDecimal
+    current_price: FloatDecimal
+    target_value: FloatDecimal
+    diff_ratio: FloatDecimal
     diff_quantity: int
     action: str  # "buy", "sell", or "hold"
-    change_vs_prev_month: Decimal | None = None
-    change_vs_start: Decimal | None = None
+    change_vs_prev_month: FloatDecimal | None = None
+    change_vs_start: FloatDecimal | None = None
 
 
 class RebalanceCalculateResponse(BaseModel):
     """Response for manual rebalance calculation."""
     portfolio_id: int
-    total_assets: Decimal
-    available_to_buy: Decimal | None = None
+    total_assets: FloatDecimal
+    available_to_buy: FloatDecimal | None = None
     items: List[RebalanceCalculateItem]
diff --git a/backend/app/schemas/strategy.py b/backend/app/schemas/strategy.py
index 23de58f..1646c57 100644
--- a/backend/app/schemas/strategy.py
+++ b/backend/app/schemas/strategy.py
@@ -7,13 +7,15 @@ from typing import Optional, List, Dict
 
 from pydantic import BaseModel, Field
 
+from app.schemas.portfolio import FloatDecimal
+
 
 class FactorWeights(BaseModel):
     """Factor weights for multi-factor strategy."""
-    value: Decimal = Field(default=Decimal("0.25"), ge=0, le=1)
-    quality: Decimal = Field(default=Decimal("0.25"), ge=0, le=1)
-    momentum: Decimal = Field(default=Decimal("0.25"), ge=0, le=1)
-    low_vol: Decimal = Field(default=Decimal("0.25"), ge=0, le=1)
+    value: FloatDecimal = Field(default=Decimal("0.25"), ge=0, le=1)
+    quality: FloatDecimal = Field(default=Decimal("0.25"), ge=0, le=1)
+    momentum: FloatDecimal = Field(default=Decimal("0.25"), ge=0, le=1)
+    low_vol: FloatDecimal = Field(default=Decimal("0.25"), ge=0, le=1)
 
 
 class UniverseFilter(BaseModel):
@@ -44,8 +46,8 @@ class QualityRequest(StrategyRequest):
 
 class ValueMomentumRequest(StrategyRequest):
     """Value-Momentum strategy request."""
-    value_weight: Decimal = Field(default=Decimal("0.5"), ge=0, le=1)
-    momentum_weight: Decimal = Field(default=Decimal("0.5"), ge=0, le=1)
+    value_weight: FloatDecimal = Field(default=Decimal("0.5"), ge=0, le=1)
+    momentum_weight: FloatDecimal = Field(default=Decimal("0.5"), ge=0, le=1)
 
 
 class StockFactor(BaseModel):
@@ -55,23 +57,23 @@ class StockFactor(BaseModel):
     market: str
     sector_name: Optional[str] = None
     market_cap: Optional[int] = None
-    close_price: Optional[Decimal] = None
+    close_price: Optional[FloatDecimal] = None
 
     # Raw metrics
-    per: Optional[Decimal] = None
-    pbr: Optional[Decimal] = None
-    psr: Optional[Decimal] = None
-    pcr: Optional[Decimal] = None
-    dividend_yield: Optional[Decimal] = None
-    roe: Optional[Decimal] = None
+    per: Optional[FloatDecimal] = None
+    pbr: Optional[FloatDecimal] = None
+    psr: Optional[FloatDecimal] = None
+    pcr: Optional[FloatDecimal] = None
+    dividend_yield: Optional[FloatDecimal] = None
+    roe: Optional[FloatDecimal] = None
 
     # Factor scores (z-scores)
-    value_score: Optional[Decimal] = None
-    quality_score: Optional[Decimal] = None
-    momentum_score: Optional[Decimal] = None
+    value_score: Optional[FloatDecimal] = None
+    quality_score: Optional[FloatDecimal] = None
+    momentum_score: Optional[FloatDecimal] = None
 
     # Composite
-    total_score: Optional[Decimal] = None
+    total_score: Optional[FloatDecimal] = None
     rank: Optional[int] = None
     fscore: Optional[int] = None
 
@@ -92,19 +94,19 @@ class StockInfo(BaseModel):
     market: str
     sector_name: Optional[str] = None
     stock_type: str
-    close_price: Optional[Decimal] = None
+    close_price: Optional[FloatDecimal] = None
     market_cap: Optional[int] = None
 
     # Valuation
-    per: Optional[Decimal] = None
-    pbr: Optional[Decimal] = None
-    psr: Optional[Decimal] = None
-    pcr: Optional[Decimal] = None
-    dividend_yield: Optional[Decimal] = None
+    per: Optional[FloatDecimal] = None
+    pbr: Optional[FloatDecimal] = None
+    psr: Optional[FloatDecimal] = None
+    pcr: Optional[FloatDecimal] = None
+    dividend_yield: Optional[FloatDecimal] = None
 
     # Per-share data
-    eps: Optional[Decimal] = None
-    bps: Optional[Decimal] = None
+    eps: Optional[FloatDecimal] = None
+    bps: Optional[FloatDecimal] = None
 
     base_date: Optional[date] = None
 
@@ -122,10 +124,10 @@ class StockSearchResult(BaseModel):
 class PriceData(BaseModel):
     """Price data point."""
     date: date
-    open: Decimal
-    high: Decimal
-    low: Decimal
-    close: Decimal
+    open: FloatDecimal
+    high: FloatDecimal
+    low: FloatDecimal
+    close: FloatDecimal
     volume: int
 
     class Config:
diff --git a/frontend/src/app/portfolio/[id]/page.tsx b/frontend/src/app/portfolio/[id]/page.tsx
index c5140f6..1394428 100644
--- a/frontend/src/app/portfolio/[id]/page.tsx
+++ b/frontend/src/app/portfolio/[id]/page.tsx
@@ -10,7 +10,7 @@ import { Tabs, TabsContent, TabsList, TabsTrigger } from '@/components/ui/tabs';
 import { TradingViewChart } from '@/components/charts/trading-view-chart';
 import { DonutChart } from '@/components/charts/donut-chart';
 import { api } from '@/lib/api';
-import { AreaData, Time } from 'lightweight-charts';
+import type { AreaData, Time } from 'lightweight-charts';
 
 interface HoldingWithValue {
   ticker: string;
@@ -31,10 +31,10 @@ interface Target {
 interface Transaction {
   id: number;
   ticker: string;
-  transaction_type: string;
+  tx_type: string;
   quantity: number;
   price: number;
-  created_at: string;
+  executed_at: string;
 }
 
 interface PortfolioDetail {
@@ -432,18 +432,18 @@ export default function PortfolioDetailPage() {
                         {transactions.map((tx) => (
                           <tr key={tx.id}>
                             <td className="px-4 py-3 text-sm text-muted-foreground">
-                              {new Date(tx.created_at).toLocaleString('ko-KR')}
+                              {new Date(tx.executed_at).toLocaleString('ko-KR')}
                             </td>
                             <td className="px-4 py-3 text-sm font-medium">{tx.ticker}</td>
                             <td className="px-4 py-3 text-sm text-center">
                               <span
                                 className={`px-2 py-1 rounded text-xs font-medium ${
-                                  tx.transaction_type === 'buy'
+                                  tx.tx_type === 'buy'
                                     ? 'bg-red-100 text-red-800 dark:bg-red-900 dark:text-red-200'
                                     : 'bg-blue-100 text-blue-800 dark:bg-blue-900 dark:text-blue-200'
                                 }`}
                               >
-                                {tx.transaction_type === 'buy' ? '매수' : '매도'}
+                                {tx.tx_type === 'buy' ? '매수' : '매도'}
                               </span>
                             </td>
                             <td className="px-4 py-3 text-sm text-right">