diff --git a/tests/test_fundamentals_lookahead.py b/tests/test_fundamentals_lookahead.py
new file mode 100644
index 000000000..696b14872
--- /dev/null
+++ b/tests/test_fundamentals_lookahead.py
@@ -0,0 +1,130 @@
+"""Historical fundamentals must not leak a live company profile (#1300).
+
+Vendor "company overview" endpoints (yfinance ``Ticker.info``, Alpha Vantage
+``OVERVIEW``) serve only present-day values: market cap, valuation multiples,
+the 52-week range and TTM income all move with today's quote, and even name,
+sector and industry shift when a company renames or is reclassified. None of it
+carries a historical vintage, so emitting it into a run dated in the past puts
+post-decision information into the analyst's context, in the same family as the
+FRED (#1275), social (#1220) and memory (#1251) leaks.
+
+Both vendors withhold on one shared rule (``date_window.withhold_live_profile``)
+so switching ``fundamental_data`` between them cannot reintroduce the leak. The
+statement tools stay point-in-time by filtering on ``curr_date``, and a live run
+is unchanged. All API access is mocked.
+"""
+from __future__ import annotations
+
+from unittest import mock
+
+import pytest
+
+from tradingagents.dataflows import alpha_vantage_fundamentals as av, date_window, y_finance
+
+_TODAY = "2026-09-07"
+_PAST = "2024-05-10"
+
+# A profile payload mixing stable-looking identity fields with market-dependent ones.
+_INFO = {
+    "longName": "Apple Inc.",
+    "sector": "Technology",
+    "industry": "Consumer Electronics",
+    "marketCap": 3_500_000_000_000,
+    "trailingPE": 34.2,
+    "fiftyTwoWeekHigh": 260.1,
+    "totalRevenue": 391_000_000_000,
+}
+
+# Values that must never reach a historical run.
+_LEAKY = ("3500000000000", "34.2", "260.1", "391000000000",
+          "Apple Inc.", "Technology", "Consumer Electronics")
+
+
+def _yf(curr_date, info=_INFO, today=_TODAY):
+    with mock.patch.object(date_window, "get_current_date", return_value=today), \
+         mock.patch.object(y_finance, "yf_retry", lambda fn: info), \
+         mock.patch.object(y_finance.yf, "Ticker"):
+        return y_finance.get_fundamentals("AAPL", curr_date)
+
+
+def _av(curr_date, today=_TODAY):
+    """Alpha Vantage path; the API call is mocked so a leak would be visible."""
+    with mock.patch.object(date_window, "get_current_date", return_value=today), \
+         mock.patch.object(av, "_make_api_request",
+                           return_value="MarketCapitalization: 3500000000000") as req:
+        return av.get_fundamentals("AAPL", curr_date), req
+
+
+@pytest.mark.unit
+class TestYFinanceHistoricalRun:
+    def test_no_profile_value_survives(self):
+        out = _yf(_PAST)
+        for leaked in _LEAKY:
+            assert leaked not in out, f"leaked live-profile value {leaked!r}"
+
+    def test_states_the_as_of_date_and_explains_itself(self):
+        # The analyst must be told why the figures are absent, so it does not
+        # read the gap as a real signal or fabricate around it.
+        out = _yf(_PAST)
+        assert f"Point-in-time as of: {_PAST}" in out
+        assert "withheld" in out
+        assert _PAST in out and _TODAY in out
+
+    def test_no_wall_clock_retrieval_stamp(self):
+        # The old header stamped datetime.now(), which is what surfaced the leak.
+        assert "Data retrieved on:" not in _yf(_PAST)
+
+    def test_the_request_is_not_even_made(self):
+        # The response would only be discarded; skipping it also avoids burning
+        # vendor quota on a call whose result cannot be used.
+        with mock.patch.object(date_window, "get_current_date", return_value=_TODAY), \
+             mock.patch.object(y_finance.yf, "Ticker") as tk:
+            y_finance.get_fundamentals("AAPL", _PAST)
+        tk.assert_not_called()
+
+
+@pytest.mark.unit
+class TestAlphaVantageHistoricalRun:
+    """The same rule must hold for the other fundamentals vendor, or switching
+    data_vendors["fundamental_data"] would silently reintroduce the leak."""
+
+    def test_overview_is_withheld(self):
+        out, _ = _av(_PAST)
+        assert "3500000000000" not in out
+        assert "withheld" in out
+        assert f"Point-in-time as of: {_PAST}" in out
+
+    def test_the_api_call_is_not_made(self):
+        _, req = _av(_PAST)
+        req.assert_not_called()
+
+    def test_live_run_still_calls_the_api(self):
+        out, req = _av(_TODAY)
+        req.assert_called_once()
+        assert "3500000000000" in out
+
+
+@pytest.mark.unit
+class TestLiveRunUnchanged:
+    def test_yfinance_current_date_returns_the_full_profile(self):
+        out = _yf(_TODAY)
+        for value in _LEAKY:
+            assert value in out
+        assert "Data retrieved on:" in out
+        assert "withheld" not in out
+
+    def test_yfinance_absent_curr_date_returns_the_full_profile(self):
+        out = _yf(None)
+        assert "Market Cap: 3500000000000" in out
+        assert "withheld" not in out
+
+
+@pytest.mark.unit
+class TestNoUsableFieldsStillRaises:
+    def test_stub_payload_raises_no_market_data(self):
+        # yfinance returns {"trailingPegRatio": None} for unknown symbols; on a
+        # live run that must stay a hard "no data", not a bare header.
+        from tradingagents.dataflows.symbol_utils import NoMarketDataError
+
+        with pytest.raises(NoMarketDataError):
+            _yf(_TODAY, info={"trailingPegRatio": None})
diff --git a/tradingagents/dataflows/alpha_vantage_fundamentals.py b/tradingagents/dataflows/alpha_vantage_fundamentals.py
index 90c89f204..56525b3ff 100644
--- a/tradingagents/dataflows/alpha_vantage_fundamentals.py
+++ b/tradingagents/dataflows/alpha_vantage_fundamentals.py
@@ -1,6 +1,7 @@
 import json
 
 from .alpha_vantage_common import _make_api_request
+from .date_window import withhold_live_profile
 
 
 def _filter_reports_by_date(result, curr_date: str):
@@ -31,13 +32,22 @@ def get_fundamentals(ticker: str, curr_date: str = None) -> str:
     """
     Retrieve comprehensive fundamental data for a given ticker symbol using Alpha Vantage.
 
+    OVERVIEW serves only present-day values and carries no historical vintage, so
+    a past ``curr_date`` withholds it rather than leaking post-decision figures
+    into a backtest (#1300); the statement endpoints below stay point-in-time via
+    ``_filter_reports_by_date``.
+
     Args:
         ticker (str): Ticker symbol of the company
-        curr_date (str): Current date you are trading at, yyyy-mm-dd (not used for Alpha Vantage)
+        curr_date (str): Analysis date, yyyy-mm-dd
 
     Returns:
         str: Company overview data including financial ratios and key metrics
     """
+    withheld = withhold_live_profile(curr_date, ticker)
+    if withheld:
+        return withheld
+
     params = {
         "symbol": ticker,
     }
diff --git a/tradingagents/dataflows/date_window.py b/tradingagents/dataflows/date_window.py
index 8b49dca26..cd27cdc32 100644
--- a/tradingagents/dataflows/date_window.py
+++ b/tradingagents/dataflows/date_window.py
@@ -13,6 +13,8 @@ from __future__ import annotations
 
 from datetime import datetime, timedelta, timezone
 
+from .utils import get_current_date
+
 
 def to_utc(dt: datetime) -> datetime:
     """Normalize a datetime to UTC-aware; a naive value is assumed to be UTC."""
@@ -28,3 +30,37 @@ def in_window(pub_dt: datetime | None, start_dt: datetime, end_dt: datetime) ->
     if pub_dt is not None:
         return to_utc(start_dt) <= to_utc(pub_dt) < end + timedelta(days=1)
     return end >= datetime.now(timezone.utc) - timedelta(days=1)
+
+
+def withhold_live_profile(curr_date: str | None, label: str) -> str | None:
+    """Notice to serve instead of a live-only company profile, or None to serve it.
+
+    Vendor "company overview" endpoints (yfinance ``Ticker.info``, Alpha Vantage
+    ``OVERVIEW``) return only present-day values: market cap, valuation
+    multiples, the 52-week range and TTM income all move with today's quote, and
+    even name, sector and industry shift when a company renames or is
+    reclassified. None of it carries a historical vintage, so serving it into a
+    run dated in the past puts post-decision information into the analyst's
+    context (#1300).
+
+    Centralized so every fundamentals vendor withholds on the same rule and says
+    the same thing; point-in-time statements come from the balance sheet, income
+    statement and cash flow tools, which filter on ``curr_date``.
+    """
+    if not curr_date:
+        return None
+    today = get_current_date()
+    if curr_date >= today:
+        return None
+    return (
+        f"# Company Fundamentals for {label}\n"
+        f"# Point-in-time as of: {curr_date}\n\n"
+        f"Profile fundamentals are withheld for this date. This vendor serves "
+        f"only present-day values ({today}) with no historical vintage: market "
+        f"cap, valuation multiples, the 52-week range and TTM income move with "
+        f"today's quote, and even the name, sector and industry reflect today "
+        f"rather than {curr_date} (companies rename and get reclassified). "
+        f"Serving them would put post-decision information into a {curr_date} "
+        f"analysis. Point-in-time fundamentals for {curr_date} are available "
+        f"from the balance sheet, income statement, and cash flow tools."
+    )
diff --git a/tradingagents/dataflows/y_finance.py b/tradingagents/dataflows/y_finance.py
index fdb49d52d..7f3f75f90 100644
--- a/tradingagents/dataflows/y_finance.py
+++ b/tradingagents/dataflows/y_finance.py
@@ -5,6 +5,7 @@ import pandas as pd
 import yfinance as yf
 from dateutil.relativedelta import relativedelta
 
+from .date_window import withhold_live_profile
 from .stockstats_utils import (
     StockstatsUtils,
     _assert_ohlcv_not_stale,
@@ -273,10 +274,22 @@ def get_stockstats_indicator(
 
 def get_fundamentals(
     ticker: Annotated[str, "ticker symbol of the company"],
-    curr_date: Annotated[str, "current date (not used for yfinance)"] = None
+    curr_date: Annotated[str, "analysis date in YYYY-MM-DD format"] = None
 ):
-    """Get company fundamentals overview from yfinance."""
+    """Get company fundamentals overview from yfinance.
+
+    ``Ticker.info`` is a present-day snapshot with no historical vintage, so a
+    past ``curr_date`` withholds it through the shared point-in-time guard
+    (``date_window.withhold_live_profile``, #1300).
+    """
     canonical = normalize_symbol(ticker)
+
+    # Guard before the request: the response would only be discarded, and the
+    # answer does not depend on it.
+    withheld = withhold_live_profile(curr_date, canonical)
+    if withheld:
+        return withheld
+
     try:
         ticker_obj = yf.Ticker(canonical)
         info = yf_retry(lambda: ticker_obj.info)
@@ -315,10 +328,7 @@ def get_fundamentals(
             ("Free Cash Flow", info.get("freeCashflow")),
         ]
 
-        lines = []
-        for label, value in fields:
-            if value is not None:
-                lines.append(f"{label}: {value}")
+        lines = [f"{label}: {v}" for label, v in fields if v is not None]
 
         # yfinance returns a stub dict (e.g. {"trailingPegRatio": None}) for
         # unknown symbols, so `info` is truthy but every field is empty. Treat