Oil, Greece turmoil set to weigh on US market By: CNBC.com News December 30, 2014 at 06:05 AM EST U.S. stock index futures signaled a lower open on Tuesday, as oil prices continued to weaken and Greece remains in focus. Read More >> Related Stocks: Apple Capital A Berhad Cisco Systems Hellenic Stock Exchanges Intel Corp Keurig Green Mountain Microsoft Sentinelone Inc Cl A Tractor Supply