** Shares of William Penn Bancorporation soar ~18% premarket
** Mid Penn Bancorp agrees to buy WMPN in $127 mln deal - a 7% premium to WMPN's last close
** "The merger enables us to accelerate our growth far more rapidly than we could as an independent company," WMPN CEO Kenneth Stephon says
** Acquisition will allow MPB to boost its presence in greater Philadelphia, as it doubles down on southeastern Pennsylvania
** MPB shares untraded before the bell
** YTD, WMPN up 3.6% vs MPB's 31% surge
(Reporting by Niket Nishant in Bengaluru)
((Niket.Nishant@thomsonreuters.com))