June 21 (Reuters) - Wall Street's main indexes opened lower on Wednesday as Federal Reserve Chair Jerome Powell remained firm in bringing inflation back to 2% target, spurring worries of more monetary tightening. The Dow Jones Industrial Average .DJI fell 63.31 points, or 0.19%, at the open to 33,990.56. (Reporting by Johann M Cherian in Bengaluru; Editing by Arun Koyyur) ((johann.mcherian@thomsonreuters.com;)) The views and opinions expressed herein are the views and opinions of the author and do not necessarily reflect those of Nasdaq, Inc.