LONDON—The dollar was on track for its best week in a month against major rivals on Friday, as the world’s reserve currency held its ground amid a selloff of riskier assets across markets. Investor sentiment has soured in recent days due to weaker economic data, rampant inflation and concerns over the pace of U.S. Federal Reserve policy tightening. Stock markets in Europe opened lower in morning trading on Friday, following the trend set in Asia and on Wall Street overnight. The dollar index—which tracks the greenback against six major peers—edged 0.1 percent lower on the day to 95.655 but was on course for a 0.5 percent weekly gain, its best performance since mid-December. Currencies seen as riskier bets including the Australian and New Zealand dollars lost ground, while those seen as safe havens such as the Japanese yen and Swiss franc strengthened. “The strength of the U.S. dollar today certainly …