* Alcoa beats expectations but cautions of slowdown
* Yum Brands defies China sluggish growth, raises outlook
* True Religion exploring sale, shares jump
* Futures: Dow off 22 pts, S&P off 1 pt, Nasdaq up 0.25 pt
By Chuck Mikolajczak
NEW YORK, Oct 10 (Reuters) - U.S. stocks were set for a slightly lower open on Wednesday as earnings season started with a warning from Alcoa about slower aluminum consumption, underscoring concerns about sluggish worldwide growth.
Other large companies warned of slowed growth, including Dow component Chevron and engine maker Cummins Inc.
Stronger demand from airplane and automobile producers helped Alcoa, the largest U.S. aluminum producer, to report third-quarter results that beat analysts' expectations. Alcoa shares lost 1.6 percent to $8.98 in premarket trade.
Lackluster growth in China, the world's second-largest economy, is expected to rein in corporate earnings in the third quarter and dent profit forecasts as the Asian nation feels the pinch of the debt crisis in the euro zone, a key trading partner.
Earlier in the week, the World Bank cut its growth forecast for East Asia on concerns China's slowdown could last longer than expected.
"You've seen very cautionary earnings results and even forward guidance. Alcoa has good earnings, but their forward guidance is lackluster. It points to a slow China and slow global growth," said Richard Weeks, managing director at HighTower Advisors in Vienna, Virginia.
"The question is when does sentiment change where (bad) news dampens the market."
Analysts forecast third-quarter earnings of Wall Street's S&P 500 companies would fall 2.3 percent from the year-ago quarter, according to Thomson Reuters data, which would be the first drop in U.S. quarterly earnings in three years.
According to data through Tuesday, 94 companies in the benchmark S&P index have issued negative outlooks, compared with 22 positive pre-announcements, for a ratio of 4.3, the weakest showing since the third quarter of 2001.
Going against general declines was Yum Brands Inc, which gained 4.8 percent to $69.20 in premarket trading. The KFC parent company had raised its full-year outlook after sales in China held up, despite that nation's cooling economy.
S&P 500 futures shed 1 point and were slightly below fair value, a formula that evaluates pricing by taking into account interest rates, dividends and time to expiration on the contract. Dow Jones industrial average futures fell 22 points, while Nasdaq 100 futures added 0.25 point.
The S&P 500 has fallen for three consecutive sessions on growing concerns about corporate profits, with the index closing on Thursday near the technical support level of 1,440.
Economic data expected Wednesday include wholesale inventories for August at 10 a.m. (1400 GMT) and the Federal Reserve's Beige Book of economic conditions at 2 p.m. (1800 GMT).
Chevron Corp dipped 2 percent to $115.02 in premarket after the second-largest U.S. oil company warned third-quarter profits would be "substantially lower" than in the previous quarter as a hurricane and maintenance curbed its oil and gas output and a fire hit its refining arm.
U.S. engine maker Cummins Inc lowered its 2012 forecast for a second time this year, citing delays in customer spending due to a weakening global economy, and said it would cut up to 1500 jobs. Cummins shares dropped 4.3 percent to $86.90 in premarket.
Earnings from warehouse chain Costco Wholesale Corp were a bright spot; the company reported a 27 percent jump in fourth quarter profit, on higher sales and membership fees. Costco shares were up 3 percent to $102.60 in premarket trade.
Coming on the heels of a 2013 profit forecast that was cut last month, FedEx Corp said it plans to slash costs at its underperforming express air freight and services divisions, with profit improvements of $1.7 billion planned at those operations over the next four years. Shares gained 3.6 percent to $88.66 in premarket.
True Religion Apparel Inc surged 24.4 percent to $26.17 in premarket trading after the denim maker said it was evaluating strategic alternatives which could include a possible sale of the company, after receiving indications of interest from third parties.