* Oil prices retreat from one-year highs
* St. Jude falls after warning on battery flaw in heart device
* Indexes down: Dow 0.38 pct, S&P 0.4 pct, Nasdaq 0.29 pct (Updates to open)
By Yashaswini Swamynathan
Oct 11 (Reuters) - U.S. stocks fell on Tuesday, dragged down by healthcare companies and Alcoa, which kicked off the earnings season on a disappointing note.
The S&P 500 healthcare sector dropped 0.71 percent as Illumina's disappointing results weighed. The company's stock lost more than a quarter of its value after the diagnostic test maker cut its third-quarter revenue forecast for the second time in a row.
Alcoa, which unofficially signals the start of the earnings period, reported revenue and profit that fell short of market expectations.
The aluminum producer's stock fell 7.7 percent on Tuesday morning.
"Earnings will begin to resolve the recent choppiness and uncertainty in the market, pushing investors one way or another," said Andre Bakhos, managing director at Janlyn Capital in Bernardsville, New Jersey.
Overall earnings of S&P 500 companies are expected to fall by 0.7 percent in the third quarter, according to Thomson Reuters data.
Oil prices fell 0.9 percent, a day after hitting a one-year high, as investors questioned whether a deal to cut output would be enough to rebalance the market by next year.
The dollar rose 0.53 percent, marking the second straight day of gains as investors priced in an 80 percent chance of a rate hike in December, according to the CME Group's FedWatch tool.
At 9:44 a.m. ET the Dow Jones Industrial Average was down 69.44 points, or 0.38 percent, at 18,259.6.
The S&P 500 was down 8.75 points, or 0.4 percent, at 2,154.91 and the Nasdaq Composite was down 15.58 points, or 0.29 percent, at 5,313.09.
All of the 11 major S&P 500 indexes were lower, with materials dropping the most by 1.08 percent.
Apple rose 2.1 percent after rival Samsung said it would scrap its Galaxy Note 7 smartphones due to safety concerns.
St. Jude dropped 3 percent in heavy premarket trading after the company warned that some of its implanted heart devices are at risk of premature battery depletion, a condition it said had been linked to two patient deaths.
Rent-A-Center dropped 34.4 percent after the company estimated third-quarter earnings to fall below analysts' expectations.
JinkoSolar rose 4.2 percent after the solar cell maker entered into an agreement for the sale of its Jinko Power downstream business in China.
Declining issues outnumbered advancing ones on the NYSE by 1,968 to 679. On the Nasdaq, 1,548 issues fell and 685 advanced.
The S&P 500 index showed two new 52-week highs and one new lows, while the Nasdaq recorded 20 new highs and 13 new lows. (Reporting by Yashaswini Swamynathan in Bengaluru; Editing by Anil D'Silva)