* Fed Chair Janet Yellen to speak at 4:00 p.m. ET
* Apple drops on Barclays price target cut
* Indexes down: Dow 0.16 pct, S&P 0.13 pct, Nasdaq 0.33 pct (Updates to early afternoon)
By Yashaswini Swamynathan
Sept 29 (Reuters) - Wall Street was lower in choppy trading late Thursday morning after two straight days of gains, pulled lower by Apple and healthcare stocks.
The S&P healthcare index dropped 1.04 percent as shares of Merck and Johnson & Johnson booked losses.
Apple fell 1.23 percent after Barclays cut its price target. The stock was the biggest drag on Wall Street.
"The markets are taking a step back after a couple of pretty good days," said Paul Nolte, portfolio manager at Kingsview Asset Management in Chicago.
"It is the end of the quarter so there are people messing around with some positions."
Investors are awaiting Federal Reserve Chair Janet Yellen's speech in Washington for clues on the health of the economy and timing of the next interest rate hike.
With just six weeks until the U.S. presidential election, some investors see a tight contest between Hillary Clinton and Donald Trump triggering volatility in certain sectors, including health insurers, drugmakers and industrials.
At 12:29 a.m. ET (1623 GMT), the Dow Jones Industrial Average was down 28.62 points, or 0.16 percent, at 18,310.62.
The S&P 500 was down 2.81 points, or 0.13 percent, at 2,168.56.
The Nasdaq Composite was down 17.55 points, or 0.33 percent, at 5,301.00.
Five of the 11 major S&P indexes were lower, with utilities falling 1.61 percent. The sector, which is sensitive to interest rate hikes, is on track to mark its fifth day of losses in a row.
Kansas City Fed President and voting member Esther George told CNBC that it was time to move ahead with a rate hike, a stand that Atlanta Fed president Dennis Lockhart echoed.
Oil prices were up about 2 percent, a day after OPEC members agreed to curb production, even as analysts raised questions about the effectiveness of the deal.
ConAgra was the top percentage gainer on the S&P, rising 7.6 percent after the company's profit beat analysts' estimate.
Intra-Cellular plunged 63.3 percent after the company said its schizophrenia drug did not show any clinically significant difference when compared with placebo.
Accenture was the top influence on the S&P, after the company reported better-than-expected quarterly revenue and profit.
Declining issues outnumbered advancing ones on the NYSE by 1,620 to 1,265. On the Nasdaq, 1,649 issues fell and 1,086 advanced.
The S&P 500 index showed 21 new 52-week highs and two new lows, while the Nasdaq recorded 60 new highs and 26 new lows. (Reporting by Yashaswini Swamynathan in Bengaluru; Editing by Anil D'Silva)