diff --git a/api/migrations/001_trading_days_schema.py b/api/migrations/001_trading_days_schema.py
new file mode 100644
index 0000000..630f188
--- /dev/null
+++ b/api/migrations/001_trading_days_schema.py
@@ -0,0 +1,111 @@
+"""Migration: Create trading_days, holdings, and actions tables."""
+
+import sqlite3
+from typing import TYPE_CHECKING
+
+if TYPE_CHECKING:
+    from api.database import Database
+
+
+def create_trading_days_schema(db: "Database") -> None:
+    """Create new schema for day-centric trading results.
+
+    Args:
+        db: Database instance to apply migration to
+    """
+
+    # Create trading_days table
+    db.connection.execute("""
+        CREATE TABLE IF NOT EXISTS trading_days (
+            id INTEGER PRIMARY KEY AUTOINCREMENT,
+            job_id TEXT NOT NULL,
+            model TEXT NOT NULL,
+            date TEXT NOT NULL,
+
+            -- Starting position (cash only, holdings from previous day)
+            starting_cash REAL NOT NULL,
+            starting_portfolio_value REAL NOT NULL,
+
+            -- Daily performance metrics
+            daily_profit REAL NOT NULL,
+            daily_return_pct REAL NOT NULL,
+
+            -- Ending state (cash only, holdings in separate table)
+            ending_cash REAL NOT NULL,
+            ending_portfolio_value REAL NOT NULL,
+
+            -- Reasoning
+            reasoning_summary TEXT,
+            reasoning_full TEXT,
+
+            -- Metadata
+            total_actions INTEGER DEFAULT 0,
+            session_duration_seconds REAL,
+            days_since_last_trading INTEGER DEFAULT 1,
+            created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
+            completed_at TIMESTAMP,
+
+            UNIQUE(job_id, model, date),
+            FOREIGN KEY (job_id) REFERENCES jobs(job_id)
+        )
+    """)
+
+    # Create index for lookups
+    db.connection.execute("""
+        CREATE INDEX IF NOT EXISTS idx_trading_days_lookup
+        ON trading_days(job_id, model, date)
+    """)
+
+    # Create holdings table (ending positions only)
+    db.connection.execute("""
+        CREATE TABLE IF NOT EXISTS holdings (
+            id INTEGER PRIMARY KEY AUTOINCREMENT,
+            trading_day_id INTEGER NOT NULL,
+            symbol TEXT NOT NULL,
+            quantity INTEGER NOT NULL,
+
+            FOREIGN KEY (trading_day_id) REFERENCES trading_days(id) ON DELETE CASCADE,
+            UNIQUE(trading_day_id, symbol)
+        )
+    """)
+
+    # Create index for holdings lookups
+    db.connection.execute("""
+        CREATE INDEX IF NOT EXISTS idx_holdings_day
+        ON holdings(trading_day_id)
+    """)
+
+    # Create actions table (trade ledger)
+    db.connection.execute("""
+        CREATE TABLE IF NOT EXISTS actions (
+            id INTEGER PRIMARY KEY AUTOINCREMENT,
+            trading_day_id INTEGER NOT NULL,
+
+            action_type TEXT NOT NULL,
+            symbol TEXT,
+            quantity INTEGER,
+            price REAL,
+
+            created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
+
+            FOREIGN KEY (trading_day_id) REFERENCES trading_days(id) ON DELETE CASCADE
+        )
+    """)
+
+    # Create index for actions lookups
+    db.connection.execute("""
+        CREATE INDEX IF NOT EXISTS idx_actions_day
+        ON actions(trading_day_id)
+    """)
+
+    db.connection.commit()
+
+
+def drop_old_positions_table(db: "Database") -> None:
+    """Drop deprecated positions table after migration complete.
+
+    Args:
+        db: Database instance
+    """
+    db.connection.execute("DROP TABLE IF EXISTS positions")
+    db.connection.commit()
diff --git a/api/migrations/__init__.py b/api/migrations/__init__.py
new file mode 100644
index 0000000..67415b7
--- /dev/null
+++ b/api/migrations/__init__.py
@@ -0,0 +1 @@
+"""Database schema migrations."""
diff --git a/tests/unit/test_trading_days_schema.py b/tests/unit/test_trading_days_schema.py
new file mode 100644
index 0000000..6b17b00
--- /dev/null
+++ b/tests/unit/test_trading_days_schema.py
@@ -0,0 +1,84 @@
+import pytest
+import sqlite3
+import importlib.util
+import sys
+import os
+
+# Import migration module with numeric prefix
+migration_path = os.path.join(os.path.dirname(__file__), '../../api/migrations/001_trading_days_schema.py')
+spec = importlib.util.spec_from_file_location("migration_001", migration_path)
+migration_001 = importlib.util.module_from_spec(spec)
+sys.modules["migration_001"] = migration_001
+spec.loader.exec_module(migration_001)
+create_trading_days_schema = migration_001.create_trading_days_schema
+
+
+class MockDatabase:
+    """Simple mock database for testing migrations."""
+    def __init__(self, connection):
+        self.connection = connection
+
+
+class TestTradingDaysSchema:
+
+    @pytest.fixture
+    def db(self, tmp_path):
+        """Create temporary test database."""
+        db_path = tmp_path / "test.db"
+        connection = sqlite3.connect(str(db_path))
+        return MockDatabase(connection)
+
+    def test_create_trading_days_table(self, db):
+        """Test trading_days table is created with correct schema."""
+        create_trading_days_schema(db)
+
+        # Query schema
+        cursor = db.connection.execute(
+            "SELECT sql FROM sqlite_master WHERE type='table' AND name='trading_days'"
+        )
+        schema = cursor.fetchone()[0]
+
+        # Verify required columns
+        assert "job_id TEXT NOT NULL" in schema
+        assert "model TEXT NOT NULL" in schema
+        assert "date TEXT NOT NULL" in schema
+        assert "starting_cash REAL NOT NULL" in schema
+        assert "starting_portfolio_value REAL NOT NULL" in schema
+        assert "daily_profit REAL NOT NULL" in schema
+        assert "daily_return_pct REAL NOT NULL" in schema
+        assert "ending_cash REAL NOT NULL" in schema
+        assert "ending_portfolio_value REAL NOT NULL" in schema
+        assert "reasoning_summary TEXT" in schema
+        assert "reasoning_full TEXT" in schema
+        assert "UNIQUE(job_id, model, date)" in schema
+
+    def test_create_holdings_table(self, db):
+        """Test holdings table is created with correct schema."""
+        create_trading_days_schema(db)
+
+        cursor = db.connection.execute(
+            "SELECT sql FROM sqlite_master WHERE type='table' AND name='holdings'"
+        )
+        schema = cursor.fetchone()[0]
+
+        assert "trading_day_id INTEGER NOT NULL" in schema
+        assert "symbol TEXT NOT NULL" in schema
+        assert "quantity INTEGER NOT NULL" in schema
+        assert "FOREIGN KEY (trading_day_id) REFERENCES trading_days(id)" in schema
+        assert "UNIQUE(trading_day_id, symbol)" in schema
+
+    def test_create_actions_table(self, db):
+        """Test actions table is created with correct schema."""
+        create_trading_days_schema(db)
+
+        cursor = db.connection.execute(
+            "SELECT sql FROM sqlite_master WHERE type='table' AND name='actions'"
+        )
+        schema = cursor.fetchone()[0]
+
+        assert "trading_day_id INTEGER NOT NULL" in schema
+        assert "action_type TEXT NOT NULL" in schema
+        assert "symbol TEXT" in schema
+        assert "quantity INTEGER" in schema
+        assert "price REAL" in schema
+        assert "FOREIGN KEY (trading_day_id) REFERENCES trading_days(id)" in schema