* Blue-chips mostly down on local institutional selling
* NCsoft falls 13 pct on weak earnings forecasts
* Healthcare shares up on bullish outlook from Obama win
SEOUL, Nov 8 (Reuters) - Seoul shares were down on Thursday morning, snapping a two-day winning streak on worries over the U.S. fiscal situation as the market responded to Obama's re-election.
The Korea Composite Stock Price Index (KOPS) fell 1.3 percent at 1,911.76 points as of 0246 GMT.
"The market is expected to trace last night's Wall Street losses and close around the 1,910-point level as the market reacts to the Obama win, while the expiry of KOSPI options contracts is having a limited contribution to market volatility," said Lee Sun-yup, analyst at Shinhan Investment Corp.
U.S. President Barack Obama faces a looming showdown over the so-called "fiscal cliff" a still-divided Congress able to block his every move after his reelection Wednesday.
Blue-chips were mostly down, with Samsung Electronics and Hyundai Motors falling 0.8 percent and 0.9 percent respectively.
Shares in builder GS Engineering & Construction tumbled 10.6 percent on weak third-quarter earnings, while online game developer NCsoft Corp shares plunged as much as 13 percent on dim earnings forecasts.
Pharmaceuticals and medical supplies manufacturers bucked the trend, with drugmaker Chongkundang Co Ltd gaining 4 percent and LG Life Sciences Ltd up 1.8 percent.
"Investor sentiment has picked up for the local healthcare sector upon Obama's re-election, as the Obama administration is expected to expand the use of generic drugs through deregulation and state support," said Kim Ki-bae, an analyst at Samsung Securities.
Local institutional investors net sold 92.4 billion Korean won ($85.11 million) worth of KOSPI shares near mid-session, weighing on the index. Declining shares vastly outnumbered winners 618 to 162.
The KOSPI 200 benchmark of core stocks was down 1.5 percent, while the junior KOSDAQ edged 0.7 percent lower.
South Korea's stock market will close one hour later than usual, at 4 p.m. (0700 GMT), after opening an hour later than usual due to national college entrance examinations. ($1 = 1085.6000 Korean won) (Reporting by Joyce Lee; Editing by Eric Meijer)