* Yellen to speak at 1:00 p.m. ET
* Fed Vice Chairman Fischer set to speak at 12:30 p.m ET
* Futures down: Dow 1 pt, S&P 4.25 pts, Nasdaq 11.5 pts (Adds details, comments, updates prices)
By Sweta Singh
March 3 (Reuters) - The S&P 500 and the Nasdaq were set to open slightly lower on Friday, as investors remained cautious ahead of Federal Reserve Chair Janet Yellen's speech, which could give more clarity on the possibility of an interest rate hike later this month.
Her speech comes after several other Fed officials this week painted an upbeat picture of the U.S. economy, stoking market expectations for a March rate hike.
Yellen is set to speak at 1:00 p.m. ET (1800 GMT) at the Executives Club of Chicago.
Fed Vice Chairman Stanley Fischer, who has backed raising interest rates, is also scheduled to give a keynote address on monetary policy in New York at 12:30 p.m. ET.
Traders have priced in a 76 percent chance of a rate hike this month, compared with roughly 30 percent at the start of the week, according to Thomson Reuters data.
"The retreat in the indices this morning suggest investors are becoming more aware of the fact the interest rate trade is likely to weigh in the coming days," Peter Cardillo, chief market economist at First Standard Financial wrote in a note.
"We suspect she will likely suggest a rate hike this month."
U.S. stock markets closed down on Thursday, as financials declined after surging a day earlier on increased expectations of a rate hike in March.
Investors also await a report from the Institute of Supply Management on its non-manufacturing index for February, which is expected to remain unchanged at 56.5. The data is expected at 10:00 a.m. ET (1500 GMT).
The dollar index, which measures the greenback's strength against a basket of six major currencies, was poised for its fourth straight weekly gain, though it was about 0.1 percent lower on Friday.
Dow e-minis 1YMc1 were down 1 point at 8:43 a.m. ET, with 34,739 contracts changing hands. S&P 500 e-minis ESc1 were down 4.25 points, or 0.18 percent, with 168,869 contracts traded. Nasdaq 100 e-minis NQc1 were down 11.5 points, or 0.21 percent, on volume of 27,662 contracts.
Among stocks, Snap Inc (NYSE:SNAP) SNAP.N , which closed up more than 40 percent in its much-awaited market debut on Thursday, was up 3.4 percent at $25.32 premarket. largest advertising group WPP (LON:WPP)'s U.S.-listed shares were down 8.2 percent at $107.35 after it cut its 2017 net sales forecast. retailer Big Lots (NYSE:BIG) BIG.N was up 5.2 percent at $54.99 after reporting a slight uptick in comparable store sales.
American Outdoor Brands' AOBC.O shares were down 7.5 percent at $17.93 as the firearm maker's full-year forecast missed estimates.