* U.S. durable goods orders rise less than expected
* No growth seen in July new home sales
* S&P's Ireland downgrade weighs
* Futures down: Dow 63 pts, S&P 8.1 pts, Nasdaq 15 pts
(Updates with durable goods data)
By Ryan Vlastelica
NEW YORK, Aug 25 (Reuters) - U.S. stock index futures pointed to a lower open on Wednesday, with pessimism spreading after much weaker-than-expected orders for long-lasting U.S. manufactured goods suggested a sharp slowdown.
The Dow and S&P are on track for a fifth straight day of losses as concerns about global growth kept traders cautious.
Durable goods orders rose by just 0.3 percent in July, and excluding transportation equipment, orders posted their largest decline in 1-1/2 years.
These numbers are "not surprising since we've seen previous data that suggested a negative print," said Joseph Battipaglia, market strategist at Stifel Nicolaus in Yardley, Pennsylvania. "There's nothing there, and consequently the U.S. economy is sliding back into recession."
S&P 500 futures fell 8.1 points and were 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 shed 63 points, and Nasdaq 100 futures lost 15 points.
July new home sales will be released at 10 a.m., and economists in a Reuters survey expect no change from the 330,000 unit annual rate in June. A revival of the housing market is considered crucial for an economic recovery, and on Tuesday, weak existing home sales data sparked a sell-off that sent stocks to seven-week lows.
"If we get a weak number (in home sales), that will further trigger an erosion in market technicals and poise the averages to retest their year lows," said Peter Cardillo, chief market economist at Avalon Partners in New York.
Standard & Poor's late on Tuesday cut its credit rating on Ireland and assigned it a negative outlook, expecting the country to face substantially higher costs to support its ailing financial institutions.
Japanese stocks hit a 16-month closing low as disappointment spread over the lack of policy action by Japan to rein in the strong yen. Japan's finance minister sharpened his rhetoric on the yen's steep gains after the Nikkei newspaper reported Japan may consider selling the yen in solo intervention if speculators drive it up.
Luxury homebuilder Toll Brothers Inc rose 2.9 percent in premarket trading to $16.66 after it swung to a third-quarter profit and said it expects gross margins before interest and write-downs to improve in its fourth-quarter.
American Eagle Outfitters Inc rose 0.7 percent to $12.58 in premarket trading after it reported second-quarter earnings.
JDS Uniphase Corp is scheduled to report after the market closes on Wednesday. The telecommunications equipment maker is expected to swing to a fourth-quarter profit.