NEW YORK (Reuters) - Stock futures extended losses on Thursday as a forecast of a quarterly loss from chemical maker DuPont and disappointing sales from retailer Target heightened worries about the deepening economic slump.
* Dow futures at session lows, down 159 points; S&P 500 futures off 16 points and below fair value.
* Before DuPont, investor sentiment had already taken a hit from pharmaceutical company Merck & Co Inc's
* Besides DuPont and Merck, AT&T
(Reporting by Ellis Mnyandu, Editing by Kenneth Barry)