Wall Street cruised to the finish of a winning week that began much bumpier. The S&P 500 rose 0.5% Friday. The Dow Jones Industrial Average added 0.5%, and the Nasdaq composite climbed 0.5%. The gains capped the S&P 500’s best week since August, but it was a roller-coaster ride. Indexes careened through jarring swings as worries built about the financial health of small and midsized banks, as well as the souring U.S.-China trade relationship. Bank stocks steadied themselves on Friday, while President Donald Trump eased some of the trade concerns after saying very high tariffs on China are not sustainable.