diff --git a/cschwabpy/models/__init__.py b/cschwabpy/models/__init__.py
index 1d90673..5ccfb22 100644
--- a/cschwabpy/models/__init__.py
+++ b/cschwabpy/models/__init__.py
@@ -319,7 +319,7 @@ def to_dataframe_row(self, strip_space: bool = False) -> List[Any]:
             self.expirationDate,
             util.ts_to_date_string(self.quoteTimeInLong),
             self.totalVolume,
-            util.ts_to_date_string(self.quoteTimeInLong),
+            self.quoteTimeInLong,  # updated_at
             self.gamma,
             self.delta,
             self.vega,
@@ -417,6 +417,7 @@ def break_down_option_map(
         strip_space: bool = False,
     ) -> Mapping[str, pd.DataFrame]:
         """Whether strip spaces in option symbols."""
+        now_unix_ts = int(util.now_unix_ts())
         result: MutableMapping[str, pd.DataFrame] = {}
         for exp_date, strike_map in optionExpMap.items():
             expiration = exp_date.split(":")[0]
@@ -434,6 +435,8 @@ def break_down_option_map(
 
                 strike_df = pd.DataFrame(all_rows)
                 strike_df.columns = OptionChain_Headers
+                # change updated_at to now_unix_ts
+                strike_df["updated_at"] = now_unix_ts
             result[expiration] = strike_df
 
         return result
diff --git a/pyproject.toml b/pyproject.toml
index 0511043..8dc2ba2 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "cschwabpy"
-version = "0.1.3.8"
+version = "0.1.3.9"
 description = ""
 authors = ["Tony Wang <ivytony@gmail.com>"]
 readme = "README.md"
diff --git a/setup.py b/setup.py
index 0e52312..782d078 100644
--- a/setup.py
+++ b/setup.py
@@ -5,7 +5,7 @@
 
 setup(
     name="CSchwabPy",
-    version="0.1.3.8",
+    version="0.1.3.9",
     description="Charles Schwab Stock & Option Trade API Client for Python.",
     long_description=long_description,
     long_description_content_type="text/markdown",