Fix user confusion about 'auto_adjust' by telling them to set it

yfinance/multi.py

@@ -24,6 +24,8 @@
 import logging
 import time as _time
 import traceback
+import warnings
+_warned_auto_adjust = False
 
 import multitasking as _multitasking
 import pandas as _pd
@@ -35,7 +37,7 @@
 
 @utils.log_indent_decorator
 def download(tickers, start=None, end=None, actions=False, threads=True, ignore_tz=None,
-             group_by='column', auto_adjust=False, back_adjust=False, repair=False, keepna=False,
+             group_by='column', auto_adjust=None, back_adjust=False, repair=False, keepna=False,
              progress=True, period="max", interval="1d", prepost=False,
              proxy=None, rounding=False, timeout=10, session=None):
     """Download yahoo tickers
@@ -88,6 +90,13 @@ def download(tickers, start=None, end=None, actions=False, threads=True, ignore_
     """
     logger = utils.get_yf_logger()
 
+    if auto_adjust is None:
+        global _warned_auto_adjust
+        if not _warned_auto_adjust:
+            warnings.warn(f"You have not set argument 'auto_adjust'. This defaults to False, but you should be setting it.", UserWarning)
+            _warned_auto_adjust = True
+        auto_adjust = False
+
     if logger.isEnabledFor(logging.DEBUG):
         if threads:
             # With DEBUG, each thread generates a lot of log messages.

yfinance/scrapers/history.py

@@ -4,6 +4,8 @@
 import numpy as np
 import pandas as pd
 import time as _time
+import warnings
+_warned_auto_adjust = False
 
 from yfinance import shared, utils
 from yfinance.const import _BASE_URL_, _PRICE_COLNAMES_
@@ -27,7 +29,7 @@ def __init__(self, data, ticker, tz, session=None, proxy=None):
     @utils.log_indent_decorator
     def history(self, period="1mo", interval="1d",
                 start=None, end=None, prepost=False, actions=True,
-                auto_adjust=True, back_adjust=False, repair=False, keepna=False,
+                auto_adjust=None, back_adjust=False, repair=False, keepna=False,
                 proxy=None, rounding=False, timeout=10,
                 raise_errors=False) -> pd.DataFrame:
         """
@@ -74,6 +76,13 @@ def history(self, period="1mo", interval="1d",
         logger = utils.get_yf_logger()
         proxy = proxy or self.proxy
 
+        if auto_adjust is None:
+            global _warned_auto_adjust
+            if not _warned_auto_adjust:
+                warnings.warn(f"You have not set argument 'auto_adjust'. This defaults to True = adjust for dividends, but you should be setting it.", UserWarning)
+                _warned_auto_adjust = True
+            auto_adjust = True
+
         start_user = start
         end_user = end
         if start or period is None or period.lower() == "max":