* Consumer confidence index hits 9-year high in September
* Oil prices plunge 3.5 pct, dollar index rises
* Indexes up: Dow 0.73 pct, S&P 0.64 pct, Nasdaq 0.88 pct (Updates to afternoon)
By Noel Randewich
Sept 27 (Reuters) - Consumer and technology stocks including Amazon led gains on Wall Street on Tuesday as some investors deemed Democrat Hillary Clinton to have won a presidential debate against Republican rival Donald Trump.
The S&P 500 technology sector rallied 1.13 percent, powered by a 2-percent gain in Microsoft and a 1.14-percent rise in Facebook.
Amazon.com increased 1.98 percent and the consumer discretionary index gained 0.93 percent higher after a report showed that the consumer confidence index for September rose to its highest level in nine years.
Following the first of three presidential debates on Monday, Trump vowed to hit Clinton harder after she put him on the defensive. With six weeks until the Nov. 8 vote, some investors see the neck-and-neck contest sparking volatility in sectors including health insurers, drugmakers and industrials.
"From a market perspective, rightly or wrongly, there is an understanding that Mrs Clinton would be a safe pair of hands, that there's very little uncertainty there," said Brad McMillan chief investment officer for Commonwealth Financial in Waltham, Massachusetts.
Still, private prison operators Corrections Corp and Geo Group fell 7.45 percent and 3.45 percent respectively after Clinton criticized states' use of for-profit prisons during the debate.
At 2:25 pm ET, the Dow Jones industrial average was up 0.73 percent at 18,227.38 point and the S&P 500 had gained 0.64 percent to 2,159.74.
The Nasdaq Composite added 0.88 percent to 5,303.81.
As well as Amazon, the consumer confidence index's increase boosted shares of Coca-Cola Co, up 1.26 percent, and Nike , which rose 1.5 percent.
"Consumer stocks seem to be catching a bit after having a hard time for probably a month or two," said Mark Spellman, portfolio manager at Alpine Funds in New York.
Oil prices plunged 3.5 percent as hopes for a deal to cut output faded as major producers meet in Algeria. The S&P 500 energy index fell 0.5 percent.
Gilead Sciences was the top drag on the S&P and the Nasdaq, falling 1.83 percent after Leerink downgraded the drugmaker's stock to "market perform".
Advancing issues outnumbered declining ones on the NYSE by a 1.51-to-1 ratio; on Nasdaq, a 1.90-to-1 ratio favored advancers.
The S&P 500 posted 12 new 52-week highs and 2 new lows; the Nasdaq Composite recorded 64 new highs and 29 new lows. (Additional reporting by Yashaswini Swamynathan in Bengaluru; Editing by Nick Zieminski)