A Chinese flag is seen in front of containers at the Yangshan Deep-Water Port, an automated cargo wharf, in Shanghai on April 9, 2018.

The U.S.-China trade war is not only putting investors on edge, but it's also making corporate executives scratch their heads when it comes to their expectations for the future.

As this earnings season starts wrapping up, a common theme emerged from hundreds of conference calls: Managers had difficulty providing concrete guidance for 2019 earnings due to the uncertainty around trade, according to David Kostin, chief U.S. equity strategist at Goldman Sachs.

"Several management teams assumed that the March 1 tariff rate increase would occur. However, some firms remained optimistic about the prospects for a deal in 2019. Additionally, firms are seeing the impact of increased uncertainty in customer decision making," Kostin said in a note.

Trade is the top-of-mind issue for companies whose revenue from China would be directly impacted from elevated tariffs. Optimism toward a long-term resolution has increased in the past couple of days as the high-level trade talks between the two countries made progress. President Donald Trump also expressed willingness to postpone the March 1 deadline reportedly by 60 days. The stock market has risen on trade hopes, with the gaining 1.7 percent this week so far.