* Gilead top drag on S&P, Nasdaq following weak forecast
* Alaska Air rises on jump in quarterly revenue
* Walt Disney rises after CEO says open to extending term
* Indexes down: Dow 0.2 pct, S&P 0.23 pct, Nasdaq 0.3pct (Updates to open)
By Yashaswini Swamynathan
Feb 8 (Reuters) - U.S. stocks were slightly lower on Wednesday, weighed down by losses in bank and healthcare stocks.
Oil prices fell 0.5 percent as an increase in U.S. crude inventories and a slump in Chinese demand implied that global oil markets remain oversupplied despite OPEC-led efforts to cut output.
The S&P 500 financial index, which has outperformed other sectors in a post-election rally, was down 0.83 percent and was on track for its third straight day of decline.
Healthcare was off 0.66 percent, dragged down by Gilead.
The drugmaker's stock, which also weighed on the S&P and the Nasdaq, was down 9.3 percent after the company projected disappointing sales for its hepatitis C drugs this year.
However, the fourth-quarter earnings season is expected to end on a high note. Combined earnings of S&P 500 companies are estimated to have risen 8.2 percent - the most in nine quarters.
At 9:43 a.m. ET (1443 GMT), the Dow Jones Industrial Average was down 40.95 points, or 0.2 percent, at 20,049.34, the S&P 500 was down 5.31 points, or 0.23 percent, at 2,287.77 and the Nasdaq Composite was down 17.04 points, or 0.3 percent, at 5,657.18.
Walt Disney was up 1.6 percent at $110.89 after Bob Iger said he was open to extending his term as chief executive officer.
Cognizant rose 4 percent to $55.96 after the IT services provider named three directors to its board and announced a $3.4 billion share buyback program, bowing to pressure from activist shareholder Elliott Management.
U.S. carrier Alaska Air rose 2.5 percent to $96.23 after the company reported a 10.7 percent jump in quarterly revenue.
Declining issues outnumbered advancers on the NYSE by 1,684 to 946. On the Nasdaq, 1,657 issues fell and 698 advanced.
The S&P 500 index showed six new 52-week highs and three new lows, while the Nasdaq recorded 26 new highs and 18 new lows. (Reporting by Yashaswini Swamynathan in Bengaluru; Editing by Anil D'Silva)