It was a day of wait with investors cautious ahead of a busy Thursday. Former FBI director Comey will address Congress, the ECB will make a policy decision, and U.K. will head to the polls. After wavering between gains and losses, stocks ended slightly higher. Chevron (CVX) was among the worst-performers on the Dow as a bruising performance on commodities markets bled over into the energy sector. Crude ended at its lowest level since May. Advanced Micro Devices (AMD) climbed for day two. The chipmaker has benefited from increased demand for its graphic processors amid a resurgence in bitcoin and cryptocurrency use. United (UAL) said involuntary denied boardings had dropped by 79% in May from a year earlier. The airline has made efforts to increase passenger incentives to give up seats on overbooked flights since its April controversy.