By Yashaswini Swamynathan

(Reuters) - U.S. stock index futures were slightly lower on Thursday, with investors on the sidelines as they wait for more clarity from the Federal Reserve its path to raise interest rates.

* Investors have been waiting for Fed Chair Janet Yellen's address at an annual meeting of global central bankers in Jackson Hole, Wyoming, for signals on the timing of the next rate hike.

* While traders have priced in a marginal chance of a hike when the Fed meets in September, Yellen's language will be assessed to see whether she endorses the recent hawkish stand taken by key policymakers, especially after considerably strong economic data.

* Data due Thursday includes a report on weekly jobless claims, which likely increased by 3,000 to 265,000. The report will be released at 8:30 a.m. ET (1230 GMT).

* Durable goods orders data rose by 3.3 percent in July after having fallen 3.9 percent the previous month, a report from the U.S. Commerce Department, also at 8:30 a.m. ET, is expected to show.

* The dollar index <.DXY>, which has enjoyed four straight days of gains, fell 0.16 percent as Yellen speech approaches.

* The movement did not seem to tell too much on oil prices, which were off about 0.18 percent as investors chose to focus the lack of potential action to address oversupply. [O/R]

* Wall Street closed lower on Wednesday, albeit in thin trading, weighed down by healthcare and materials stocks.

* Shares of Mylan <MYL.O> rose 3 percent to $44.45 in premarket trading after the drugmaker would reduce the patient cost of its severe allergy treatment drug EpiPen.

* Amgen <AMGN.O> slipped 1.2 percent after the drugmaker said the FDA had issued a complete response letter for a drug.

* Tiffany <TIF.N> rose 1.6 percent to $70 after the company reported a better-than-expected quarterly profit.

* Workday <WDAY.N> jumped 10.5 percent to $88 after the maker of human resources software reported a 34 percent rise in quarterly sales.

Futures snapshot at 7:11 a.m. ET:

* Dow e-minis <1YMc1> were down 43 points, or 0.23 percent, with 18,389 contracts changing hands.

* S&P 500 e-minis <ESc1> were down 5.5 points, or 0.25 percent, with 141,111 contracts traded.

* Nasdaq 100 e-minis <NQc1> were down 11.75 points, or 0.25 percent, on volume of 19,733 contracts.

(Reporting by Yashaswini Swamynathan in Bengaluru; Editing by Savio D'Souza)