* Micron gains on bullish brokerage comment
* Microchip provides upbeat sales outlook
* Energy stocks slide as oil drops 1%
* Indexes: Dow down 0.26%, S&P off 0.23%, Nasdaq flat (For a live blog on the U.S. stock market, click or type LIVE/ in a news window)
By Sruthi Shankar and Susan Mathew
Jan 7 (Reuters) - Wall Street's main indexes fell on Tuesday, dragged down by oil and healthcare stocks as investors nervously awaited further developments on the U.S.-Iran conflict.
Energy stocks were down 0.9% as oil prices surrendered gains made over the previous days, while healthcare stocks fell 0.6%, led by Merck that was hit by mixed results in its Phase 3 trial of a cancer drug.
Equity markets have been trying to shake off concerns from escalating tensions between Washington and Tehran after the killing of a top Iranian general last week by the United States.
After closing higher on Monday and steadying into the open on Tuesday, U.S. stocks lost momentum again.
"The reason why we are modestly negative here is obviously the tension in the Middle East and the noise coming out around it," said Phil Blancato, chief executive officer of Ladenburg Thalmann Asset Management in New York.
"I think the market is being very patient here, just waiting for news from one side or the other and if there is any kind of retaliatory issue with the US. It is not a significant move."
Latest data showed new orders for U.S.-made goods fell in November, pulled down by steep declines in demand for machinery and transportation equipment, pointing to sustained weakness in manufacturing.
However, another reading on the non-manufacturing sector activity for November came in slightly better than expected.
Helping the tech-heavy Nasdaq outperform on Tuesday was Micron Technology Inc, which rose 6% after Cowen & Co upgraded the chipmaker to "outperform" on an earlier-than-expected recovery in the memory market.
The brokerage also raised its rating on hard-disk maker Western Digital Corp to "outperform". Its shares rose 5.2%.
Another bright spot in the semiconductor space was Microchip Technology, which rose 5.1% after raising the mid-point of its sales forecast for the third quarter.
At 10:21 a.m. ET, the Dow Jones Industrial Average was down 74.66 points, or 0.26 percent, at 28,628.72, the S&P 500 was down 7.42 points, or 0.23 percent, at 3,238.86 and the Nasdaq Composite was up 2.63 points, or 0.03 percent, at 9,074.09.
Market participants are also awaiting the fourth-quarter reporting season, which begins in earnest next week. Earnings for S&P 500 companies are expected to dip 0.5%, the second consecutive quarter of decline, according to Refinitiv IBES data.
Goldman Sachs Group Inc rose 1.3% after the Wall Street bank said it has overhauled its main business units ahead of its quarterly results next week.
Shares in Apache Corp jumped 20.3% after it and France's Total said they made a major oil discovery offshore Suriname with the closely watched Maka-Central 1 well.
Tesla Inc gained 2% after the company launched its Model Y electric sports utility vehicle at its new Shanghai factory.
Declining issues outnumbered advancers for a 1.61-to-1 ratio on the NYSE and a 1.38-to-1 ratio on the Nasdaq.
The S&P index recorded 24 new 52-week highs and one new low, while the Nasdaq recorded 57 new highs and six new lows. (Reporting by Sruthi Shankar, Medha Singh and Susan Mathew in Bengaluru; Editing by Sriraj Kalluvila and Maju Samuel)