US STOCKS-Wall St ends down as Fed officials weigh in
* Top Fed officials voice contrasting viewpoints about decision
* Caterpillar drags Dow after reporting sales
* Trading volume heavy due to "quadruple witching," index rebalancing
* FireEye, Rocket Fuel shares soar in trading debut
* Blackberry plunges after outlook
* Dow off 1.19 pct; S&P off 0.72 pct; Nasdaq off 0.39 pct
By Chuck Mikolajczak
NEW YORK, Sept 20 (Reuters) - U.S. stocks fell on Friday as investors puzzled over the Federal Reserve's decision to maintain its stimulus measures as they heard opposing viewpoints from top Fed officials.
Despite lower closes in the past two sessions, the major stock indexes ended higher for the week. The Dow rose 0.6 percent, the S&P gained 1.3 percent and the Nasdaq advanced 1.4 percent. Continued...