* Futures down: Dow 6 pts, S&P 1.75 pts, Nasdaq 4.75 pts
By Yashaswini Swamynathan
Sept 29 (Reuters) - U.S. stock index futures were little changed on Thursday as oil prices lost ground and investors braced for a heavy dose of economic data and comments from Federal Reserve officials.
* An agreement among major oil producing countries to curb output resulted in a near 6 percent surge in Brent crude prices on Wednesday, but the lack of details of the deal led to profit taking a day later. The commodity was down 0.88 percent.
* Wall Street ended higher on Wednesday as the oil rally lifted shares of energy companies.
* Yellen speaks on banking and the economy at 4:00 p.m. ET (2000 GMT) in Washington and her comments will be parsed for any hints on the future path of interest rates.
* Fed Board Governor Jerome Powell and Kansas City Fed President Esther George, members who vote on interest rates, are also among those scheduled to speak on Thursday.
* The markets have been captive to every deliberation by the central bank as its officials remain divided over whether the U.S. economy is strong enough to absorb a rate hike in the near term.
* Analysts say the markets are likely to face increased volatility as the U.S. presidential election nears, while investors also prepare for the upcoming third-quarter corporate earnings season.
* Data on watch for Thursday includes the final estimate of second-quarter gross domestic product, which likely increased to 1.3 percent from the prior estimate of 1.1 percent. The report is due at 8:30 a.m. ET (1230 GMT).
* Initial jobless claims rose to 260,000 last week, a report also at 8:30 a.m. ET is expected to show.
* Shares of PepsiCo rose 2.3 percent to $109.90 premarket after the beverage giant reported quarterly revenue that beat analysts' estimate.
* Ebay rose 2.4 percent after Deutsche Bank upgraded the e-commerce platform's rating to "buy" and raised its price target.
* Intra-Cellular plunged 65.76 percent to $14.50 after the company said its schizophrenia drug did not show any clinically significant difference when compared with placebo.
* Fitbit was down 4.9 percent after pacific Crest downgraded its stock to "underweight".
Futures snapshot at 6:51 a.m. ET:
* Dow e-minis were down 6 points, or 0.03 percent, with 15,554 contracts changing hands.
* S&P 500 e-minis were down 1.75 points, or 0.08 percent, with 104,153 contracts traded.
* Nasdaq 100 e-minis were down 4.75 points, or 0.1 percent, on volume of 13,695 contracts. (Reporting by Yashaswini Swamynathan in Bengaluru; Editing by Anil D'Silva)