diff --git a/tradingagents/dataflows/alpha_vantage_common.py b/tradingagents/dataflows/alpha_vantage_common.py
index 409ff29e..e0a4bade 100644
--- a/tradingagents/dataflows/alpha_vantage_common.py
+++ b/tradingagents/dataflows/alpha_vantage_common.py
@@ -1,4 +1,5 @@
 import os
+import re
 import requests
 import pandas as pd
 import json
@@ -14,6 +15,10 @@ def get_api_key() -> str:
         raise ValueError("ALPHA_VANTAGE_API_KEY environment variable is not set.")
     return api_key
 
+def _sanitize_url(url: str) -> str:
+    """Remove sensitive API key values from a URL string for safe logging."""
+    return re.sub(r'([\?&]apikey=)[^&]+', r'\1***REDACTED***', url, flags=re.IGNORECASE)
+
 def format_datetime_for_api(date_input) -> str:
     """Convert various date formats to YYYYMMDDTHHMM format required by Alpha Vantage API."""
     if isinstance(date_input, str):
@@ -41,33 +46,53 @@ class AlphaVantageRateLimitError(Exception):
 
 def _make_api_request(function_name: str, params: dict) -> dict | str:
     """Helper function to make API requests and handle responses.
-    
+
+    The Alpha Vantage API requires the key to be supplied as a query parameter.
+    To reduce the risk of accidental key exposure in logs and error messages the
+    key is:
+      - never stored in the intermediate ``api_params`` dict, and
+      - redacted from any URL that appears in exception text via
+        ``_sanitize_url()``.
+
     Raises:
         AlphaVantageRateLimitError: When API rate limit is exceeded
     """
-    # Create a copy of params to avoid modifying the original
+    # Create a copy of params to avoid modifying the original.
+    # The API key is intentionally kept out of this dict so it does not appear
+    # in local state that could be logged or serialised for debugging.
     api_params = params.copy()
     api_params.update({
         "function": function_name,
-        "apikey": get_api_key(),
         "source": "trading_agents",
     })
-    
+
     # Handle entitlement parameter if present in params or global variable
     current_entitlement = globals().get('_current_entitlement')
     entitlement = api_params.get("entitlement") or current_entitlement
-    
+
     if entitlement:
         api_params["entitlement"] = entitlement
     elif "entitlement" in api_params:
         # Remove entitlement if it's None or empty
         api_params.pop("entitlement", None)
-    
-    response = requests.get(API_BASE_URL, params=api_params)
-    response.raise_for_status()
+
+    # Merge the API key into request_params only at call-time so the key is
+    # not retained in any longer-lived variable.
+    request_params = {**api_params, "apikey": get_api_key()}
+
+    try:
+        response = requests.get(API_BASE_URL, params=request_params)
+        response.raise_for_status()
+    except requests.exceptions.HTTPError as exc:
+        # Sanitize the request URL before it propagates to callers / logs.
+        safe_url = _sanitize_url(exc.response.url if exc.response is not None else "")
+        raise requests.exceptions.HTTPError(
+            f"HTTP error {exc.response.status_code} for URL: {safe_url}",
+            response=exc.response,
+        ) from exc
 
     response_text = response.text
-    
+
     # Check if response is JSON (error responses are typically JSON)
     try:
         response_json = json.loads(response_text)