solves #2026

Solution that checks the offset of the opening time of the stock exchange (mod 30 minutes) and adds it to the quotes

yfinance/scrapers/history.py

@@ -227,7 +227,9 @@ def history(self, period="1mo", interval="1d",
         # 2) fix weired bug with Yahoo! - returning 60m for 30m bars
         if interval.lower() == "30m":
             logger.debug(f'{self.ticker}: resampling 30m OHLC from 15m')
-            quotes2 = quotes.resample('30min')
+            exchangeStartTime = pd.Timestamp(self._history_metadata["tradingPeriods"][0][0]["start"], unit='s')
+            offset = str(exchangeStartTime.minute % 30)+"min"
+            quotes2 = quotes.resample('30min', offset=offset)
             quotes = pd.DataFrame(index=quotes2.last().index, data={
                 'Open': quotes2['Open'].first(),
                 'High': quotes2['High'].max(),