US STOCKS-Wall St falls for 3rd day as earnings fall short
* Dow in the red for the year
* Caterpillar falls after lower quarterly profit
* Amazon, Visa shares gain in after-hours trading
* Indexes down: Dow 0.7 pct, S&P 0.6 pct, Nasdaq 0.5 pct (Updates close with volume, Visa up after the bell)
By Caroline Valetkevitch
July 23 (Reuters) - U.S. stocks fell for the third straight day on Thursday after disappointing corporate results and forecasts added to concerns about the U.S. profit outlook.
The Dow Jones industrial average fell back into the red for the year, with 3M, American Express and Caterpillar contributing the most to the average's fall.
The Dow Jones transportation average was off 2.1 percent, with only one of its 20 components ending in the black. Union Pacific, down 5.7 percent at $92.12 after posting a lower quarterly profit, led the decline in transportation shares and was among the S&P 500's biggest drags.
"The initial take on big earnings reports has been lukewarm at best," said Bruce Zaro, chief technical strategist at Bolton Global Asset Management in Boston. Continuación...