Stocks sold off around the world Friday, with US equities erasing what would’ve been a sixth weekly gain as Turkey’s economic crisis deepened. The dollar capped its best week since June. The S&P 500 Index slumped in thin trading, zapping gains that had taken it within striking distance of an all-time high. European and emerging-market equities bore the brunt of selling, with losses of more than 1 percent after the United States escalated a diplomatic row that tipped Turkey’s economy deeper into crisis. The 10-year yield slid below 2.9 percent as price data reinforced the Federal Reserve’s rate-hike intentions and investors sought havens. A government report on agriculture stocks sent soybean, cotton, and wheat futures tumbling. Oil settled above $67 a barrel. Geopolitical tensions between the United States and other countries set the tone for markets last week, with a speech from President Recep Erdogan doing little to quell investor angst that Turkey’s crisis will spread to other economies. The Trump administration doubled tariffs, exacerbating the issue. Earlier last week, China responded to the Trump administration’s trade war volley with additional tariffs of its own. The ruble fell the most since the 2015 oil shock after the United States announced new sanctions on Russia over a nerve-agent attack in Britain. Also, Elon Musk roiled Tesla Inc.’s shares with a tweet signaled he’d take the firm private. The stock ended lower than where it was at the time of the missive.