Via Goldman:
The tariff impact on S&P 500 EPS through lower revenues is minimal. S&P 500 firms derive just 2% of aggregate sales explicitly from China. Even a global trade war where every country imposes a 5% tariff on all trading partners would have a muted revenue impact. Our economists estimate the demand-side effects of such a scenario would reduce US GDP by roughly 20 bp and world GDP by 10 bp. This scenario would translate to a 1% reduction in 2019 S&P 500 EPS (from $170 to $169), given our EPS model’s sensitivity to GDP growth.
Tariffs pose a larger threat to S&P 500 EPS through lower margins. We consider adverse scenarios in which tariffs are placed on all imports from China or globally. For all US industry, roughly 15% of cost of goods sold (COGS) is imported. We assume that S&P 500 companies, which are more global in nature and have more complex supply chains, import roughly 30% of COGS. This is consistent with the 29% of S&P 500 sales is generated outside the US. Imports from China comprise 18% of total US imports.