$Tesla Motors(TSLA)$ $Netflix(NFLX)$ $SPDR S&P 500 ETF Trust(SPY)$ $Goldman Sachs(GS)$ April 19 (Reuters) - U.S. stock index futures fell on Wednesday as Treasury yields rose on expectations the Federal Reserve could keep interest rates higher for longer, while a slide in Tesla and Netflix shares was set to weigh on the tech-heavy Nasdaq.Tesla Inc dropped 2.8% in premarket trading after the electric-vehicle maker cut prices on some of its Model Y and Model 3 vehicles in the United States, the sixth time it has lowered prices this year.The company is due to report January-March quarter results after the closing bell on W