US STOCKS-Wall St set to open flat ahead of Yellen's speech
* Private sector adds most jobs since June
* Yellen to speak at 12:25 p.m. ET
* November jobs report expected on Friday
* Yahoo shares rise after reports of sale of core unit
* Futures: Dow down 12 pts, S&P up 0.5 pts, Nasdaq up 4.25 pts (Adds details, comment, updates prices)
By Tanya Agrawal
Dec 2 (Reuters) - U.S. stock index futures were little changed on Wednesday as investors held off on taking big positions ahead of Federal Reserve Chair Janet Yellen's speech.
Data showed that the private sector added the most jobs since June as markets awaited clues from Yellen on an expected interest rate increase on Dec. 16.
Yellen will speak before the Economic Club of Washington at 12:25 p.m. ET (1625 GMT). She also testifies on the economic outlook before a joint committee of Congress on Thursday. Continuación...