U.S. stock index futures slipped lower Friday, ending the week on a negative note as investors continue to monitor the ongoing conflict between Israel and Iran that has now entered its second week.

At 05:25 ET (09:25 GMT), Dow Jones Futures fell 80 points, or 0.2%, S&P 500 Futures dropped 14 points, or 0.2%, and Nasdaq 100 Futures slipped 54 points, or 0.3%. 

Wall Street was closed for the Juneteenth holiday on Thursday, and investors have been wary of placing any big bets this week. The S&P 500 is up marginally so far this week with a gain of 0.1%. The 30-stock Dow has lost 0.1%, while the Nasdaq has advanced about 1%.