US STOCKS-Wall St ends flat after six-day rally, energy rises
* Wisconsin Energy to buy Integrys for $9.1 bln
* Industrial shares among the weakest of the day
* ParkerVision plummets on its heaviest-ever volume
* Indexes: Dow down 0.2 pct, S&P down 0.1 pct, Nasdaq flat (Updates to close)
By Ryan Vlastelica
NEW YORK, June 23 (Reuters) - U.S. stocks ended a quiet session on Monday essentially unchanged as investors found few reasons to keep buying following a six-day rally in the S&P 500, though merger activity lifted energy shares.
The S&P was coming off its longest streak of advances since mid-April, and both it and the Dow had closed at records on Friday. While Wall Street's uptrend is still viewed as intact, investors are looking for catalysts to deliver more robust gains, and recent economic data has been mixed.
U.S. May existing home sales rose at more than twice the rate of growth expected, while a preliminary read on June manufacturing hit its highest since May 2010. Other surveys of manufacturers gave positive signals for the global economic outlook, but dark clouds remained over Europe.