US STOCKS-Dow, S&P slightly lower ahead of Yellen speech
* Yellen to speak in New York at 12:20 p.m. ET
* Chipotle down after rating downgrade
* Tech stocks help Nasdaq eke out small gain
* Dow down 0.23 pct, S&P down 0.10 pct, Nasdaq up 0.41 pct (Updates to early afternoon)
By Yashaswini Swamynathan
March 29 (Reuters) - A decline in oil prices kept the S&P 500 and the Dow slightly in the red on Tuesday, minutes ahead of Federal Reserve Chair Janet Yellen's speech on monetary policy.
Yellen, who is due to speak before the Economic Club of New York at 12:20 p.m. ET (1620 GMT), will make her first remarks since the Fed's meeting in March.
The central bank has said it will depend on economic data before it makes a decision on rates, but several policymakers have voiced support for more than one increase this year.
Investors will keep a close eye on Yellen's speech as they look for fresh drivers that could push stocks higher. Continuación...