* Fed Chair Yellen set to speak at 3:00 p.m. ET
* Target's weak sales, forecast cut weigh on retailers
* UnitedHealth down for third day, top drag on Dow
* Dow down 0.28 pct, S&P down 0.02 pct, Nasdaq up 0.07 pct (Updates to early afternoon)
By Yashaswini Swamynathan
Jan 18 (Reuters) - The S&P 500 and the Nasdaq were little changed in choppy trading on Wednesday as gains in tech stocks offset a weakness in retail sector, while the Dow was pulled lower by healthcare shares.
The S&P 500 consumer discretionary sector was the biggest drag on the broader index, falling 0.4 percent as Target weighed.
The big-box retailer's shares fell 5.5 percent - their biggest single-day drop since August - after the brick-and-mortar chain reported dismal results for the holiday season and cut its quarterly earnings forecast.
Bigger rival and Dow component Wal-Mart was off 0.8 percent.
Federal Reserve Chair Janet Yellen is scheduled to speak at 3:00 p.m. ET (2000 GMT). Investors will parse her comments to see if she joins other policymakers in suggesting more aggressive interest rate hikes to ward off potential inflationary pressure from Donald Trump's proposed policies.
A frenetic post-election rally in U.S. equities has hit a speed bump in recent weeks as investors wait for Trump to work on his campaign promises.
The markets, which have received little detail on his policy plans, expect to get more insight during his inaugural speech on Friday.
At 12:29 a.m. ET (1729 GMT), the Dow Jones Industrial Average was down 54.72 points, or 0.28 percent, at 19,772.05 and the S&P 500 was down 0.43 points, or 0.02 percent, at 2,267.46.
The Nasdaq Composite was up 3.67 points, or 0.07 percent, at 5,542.40.
Six of the 11 major S&P 500 sector indexes were higher, with technology and industrials giving the broader index its biggest boost.
UnitedHealth, which has risen more than 10 percent since the election, was off 2.6 percent at $156.36 and was the biggest drag on the Dow. All four health stocks on the index were trading lower.
Qualcomm rose 1.6 percent and gave the biggest lift to the technology sector after Morgan Stanley said in a note that the U.S. government may be reluctant to pursue an antitrust case against the company.
3M was the top stock among industrials, rising about 1 percent on a price target raise from Jefferies.
Bank of America gave the biggest boost to the S&P 500. Goldman Sachs lost 1.7 percent and Citigroup 2 percent despite reporting strong quarterly profits.
Consumer prices edged up 0.3 percent in December, while industrial output rebounded in the month - continuing the trend of sustained economic growth.
Advancing issues outnumbered decliners on the NYSE by 1,462 to 1,350. On the Nasdaq, 1,402 issues rose and 1,330 fell.
The S&P 500 index showed 12 new 52-week highs and three new lows, while the Nasdaq recorded 52 new highs and 20 new lows. (Reporting by Yashaswini Swamynathan in Bengaluru; Editing by Anil D'Silva)