* Futures off: Dow 21 pts, S&P 4 pts, Nasdaq 6 pts
NEW YORK, Oct 27 (Reuters) - U.S. stock index futures dipped on Monday after the S&P 500 closed its best week in nearly two years on Friday and ahead of data on U.S. services sector growth and home sales.
* Earnings continue to trickle in, with Merck reporting lower than expected third quarter revenue though it beat earnings forecasts thanks to cost cuts. Its shares were little changed in early trading.
* German business sentiment fell in October for a sixth straight month to its lowest level in almost two years, adding to recent concerns the largest European economy may continue to struggle to grow.
* Sarepta Therapeutics shares fell 25.7 percent in premarket trading after it said the U.S. Food and Drug Administration requested additional data regarding a marketing application for its experimental muscle disorder drug.
* Shares of Brazilian companies traded in the United States tumbled after incumbent Dilma Rousseff won reelection in a runoff vote, defeating centrist and market favorite Aecio Neves by a slim margin. Petrobras ADRs slumped 16.1 percent in premarket trading and Vale lost 4.9 percent.
* The S&P 500 closed its best week since January 2013 helped on Friday by earnings from Microsoft and Procter & Gamble and as concerns eased over the possible spread of Ebola in the United States.
Futures snapshot at 7:34 a.m.:
* S&P 500 e-minis fell 4.25 points, or 0.22 percent, with 167,042 contracts changing hands.
* Nasdaq 100 e-minis were down 6 points, or 0.15 percent, in volume of 25,549 contracts.
* Dow e-minis lost 21 points, or 0.13 percent, with 27,303 contracts changing hands.
Reporting by Rodrigo Campos; Editing by Bernadette Baum