U.S. stocks were modestly higher after four days of heavy losses, but investors remained on edge after China and the European Union announced they would retaliate against President Trump’s tariffs.

The Dow Jones Industrial average rose 0.4% as of mid-morning trading but it has been swinging between gains and losses. The S&P 500 was up 0.7% while the Nasdaq was up over 1.7%.

But sentiment remained fragile. China on Wednesday announced an additional 50% retaliatory tariff on all U.S. imports, bringing the total tariff level to 84%. The EU separately said it would impose retaliatory tariffs on €22 billion worth of American products such as soybeans, motorcycles, and orange juice in response to U.S. steel and aluminum tariffs.

The two major economies are responding after Trump’s latest round of tariffs went into effect overnight, including a 104% levy on China.