Japanese stocks fell for a fourth day Thursday, extending a global slide that has seen shares post their worst start to a year since 2000, after China again cut the reference rate for the yuan and trading in the world's second-biggest equity market was halted to halt a plunge.

"A weaker yuan against the yen hits Japanese stocks directly," said Kazuhiro Miyake, chief strategist at Daiwa Securities Co. in Tokyo. "As long as the yuan continues to weaken, you can make money by selling Japanese stocks. In August, investors who made money with that trade are probably doing it again now."

On Thursday, the Topix index sank 2.1 percent to 1,457.94 in Tokyo to close at the lowest level since Oct. 2, as energy explorers led declines after the price of oil tumbled. The Nikkei 225 stock average dropped 2.3 percent to 17,767.34, falling below the 18,000 mark for the first time since Oct. 15. The yen traded at 17.64 per yuan in offshore trading, near the highest since 2014, after China's central bank cut its currency's reference rate against the dollar by 0.5 percent.