U.S. stock index futures were muted on Friday, with Wall Street's main indexes on track for their second-straight week of gains, while uncertainty about President Donald Trump's trade policies also prevailed.

U.S. agricultural commodities fell back Wednesday from recent strength after President Trump announced new threats to apply tariffs on Chinese shipments to the U.S., as the ag market is expected to be one of the main industries that would be impacted by the economic fallout of new tariffs.