* Oil prices sink, hitting energy stocks
* Alcoa Q1 revenue misses estimates, stock slides
* Japan raises nuclear crisis level to same as Chernobyl
* Dow off 1 pct, S&P off 0.8 pct, Nasdaq off 1 pct
* For up-to-the-minute market news see [STXNEWS/US] (Updates to late afternoon, changes byline)
By Caroline Valetkevitch
NEW YORK, April 12 (Reuters) - U.S. stocks dropped on Tuesday as falling oil prices took money out of the market's best-performing sector, while Alcoa's leaner-than-expected revenue disappointed investors.
Energy stocks led the S&P 500's losses, with the S&P
Energy Index <.GSPE> down 3.1 percent. Dow component Chevron
Corp
Oil prices tumbled for a second day following a Goldman
Sachs forecast calling for a fall of almost $20 in the price
of Brent crude oil
U.S. crude is up about 16 percent since the start of the year largely because of unrest in oil-heavy regions of the Middle East and North Africa, while the S&P energy index is up 11.1 percent -- well above the S&P 500's gains of 4.6 percent since the start of the year.
A reversal in oil prices could signal the same in oil-related stocks, some strategists suggest.
"The leadership has been for longest time in those sectors that are highly related to global growth and commodity prices. So once the commodity space starts rolling over, then equities are poised to follow," said Robbert Van Batenburg, head of equity research at Louis Capital in New York.
Alcoa Inc
Materials stocks in general were down with declines in metals prices, with worries that Japan's massive earthquake and a nuclear crisis could weaken recovery prospects in the world's third-largest economy.[ID:nLDE73B066]
The Dow Jones industrial average <.DJI> was down 127.79 points, or 1.03 percent, at 12,253.32. The Standard & Poor's 500 Index <.SPX> was down 10.44 points, or 0.79 percent, at 1,314.02. The Nasdaq Composite Index <.IXIC> was down 27.35 points, or 0.99 percent, at 2,744.16.
Japan raised the severity of the Fukushima nuclear power plant accident to the highest level on the International Nuclear and Radiological Event Scale, putting it on par with the Chernobyl 1986 disaster.
"Japan is looming large in background," Van Batenburg said, noting warnings about supply issues by Japanese companies. "When coming into earnings season with that kind of outlier, people are going to take a step back."
The S&P Materials Index <.GSPM> fell 1.2 percent while
U.S.-traded shares of Rio Tinto