Stocks on Wall Street ended a volatile week with a bounce on Friday, while government bond markets continued to signal investor worry about the impact of new import taxes, as China raised its tariffs on American-made products to 125 percent.

The S&P 500 fell as much as 0.9 percent in morning trading before rallying through the afternoon to a gain of 1.8 percent, taking the week’s rise to 3.8 percent. Last week, the index recorded its worst tumble since the 2008 financial crisis.

Markets around the world have veered sharply between large gains and losses amid the turmoil and confusion caused by President Trump’s pronouncements on tariffs.

In the government bond market, the 10-year Treasury yield rose again on Friday, taking its gains since last week to roughly 0.5 percentage points, a huge move in a market that underpins corporate and consumer borrowing. The U.S. dollar slumped 0.8 percent on Friday, to its lowest level in about two years.

Analysts at ING noted that there was a “confidence crisis” in the dollar as U.S. assets lost some of their haven appeal.

All week, markets have been whipped around by the varying intensity and focus of Mr. Trump’s trade policy. Steep “reciprocal” tariffs were imposed on dozens of countries and then, hours later, paused for 90 days. At the same time, the United States and China ratcheted up tariffs on the trade between them.