BEIJING—Global stock markets were mixed Thursday and oil prices jumped another $5 as Russian forces whose attack on Ukraine has roiled financial markets bombarded the country’s second-largest city and besieged two ports. The economic fallout from the Russian invasion expanded, with Fitch Ratings and Moody’s Ratings cutting Russia’s credit rating. They said the invasion and Western sanctions have hurt Moscow’s ability to repay debts and raised risks for the economy and stability. In early trading, the FTSE 100 in London lost 0.6 percent to 7,385.44 and Frankfurt’s DAX shed 1.1 percent to 13,849.55. The CAC in Paris slipped 0.5 percent to 6,467.16. On Wall Street, the future for the S&P 500 was 0.2 percent lower and the contract for the Dow Jones Industrial Average lost 0.1 percent. The London Stock Exchange said it had suspended trading in shares of 27 companies with links to Russia, including some of the biggest …