Goldman Sachs warned its clients that if President Donald Trump does implement a protectionist trade policy, it could start a global trade war and lead to a market drop.

The firm mentioned recent news reports that the administration may be considering tariffs on imports. In the event of a trade conflict, the bank recommends investors buy companies with higher domestic sales exposure.

“We remain constructive on global equity markets and continue to be overweight within our asset allocation on a 12-month horizon. … One potential risk to our central case is that global growth slows, or profits are hit, by increased US tariffs on trade and the possibility of an escalating global trade war,” Goldman’s chief global equity strategist, Peter Oppenheimer, wrote in a note to clients Thursday. “While this is not our expectation, this topic has once again become a focus for markets and could take center-stage at the forthcoming G-20 meeting.”

Oppenheimer is referring to the July 7 to July 8 G-20 summit of leaders of the world’s biggest economies in Hamburg. The G-20 consists of 19 countries plus the European Union, which represent 80 percent of global output.

The strategist said lofty valuations, high corporate profit margins and low volatility are reasons why a trade conflict could spark a larger negative impact for global equities. He cited how the S&P 500’s valuation looks “very stretched” with metrics such as forward price-to-earnings and price-to-book value are near 90 percent historical percentile levels since 1976.

In terms of which markets have the most downside from rising trade tensions, Oppenheimer noted 69 percent of the US companies’ sales are domestic versus 64 percent for Japan and 53 percent for Europe.

“The impact of tariffs would likely be felt most acutely in Asia and Latin America, given the rapid growth in their exports to the US and the high labor content in the production of these exports. However, European equity markets would not be immune,” he wrote.

In terms of specific US sectors, technology stocks with 59 percent of sales overseas and materials companies with 48 percent foreign sales exposure are most at risk, according to the strategist.

“Below the surface of the market, trade conflict would benefit the performance of the most domestic-facing US stocks relative to the most foreign-facing firms,” he wrote.

As result, if a trade war does occur, Oppenheimer recommends the Goldman Sachs “domestic sales” stock basket over the firm’s “international sales” list.

Here are 7 companies in Goldman’s domestic sales basket.

Note: Goldman’s domestic sales basket list is as of Jan. 18, 2017