BUZZ-U.S. stocks weekly: Trade is the headwind

** S&P 500 ends week essentially flat as economic growth concerns and trade worries linger ** Indeed, the SPX is still just south of another battle line ** This as the DJI goes toe-to-toe with support , while the NYSE Composite has dissipating energy ** That said, "China" is still the key trading floor buzzword ** In the end, majority of sectors fall: Energy, materials and financials slide, while tech and defensive plays lift ** Energy slumps 3.3 pct. Biggest SPX loser An