Japanese stocks had their worst slump since they entered a bear market a month ago, after a poor U.S. manufacturing reading rekindled worries about a U.S. recession, while a selloff in global tech shares and a firmer yen also weighed on sentiment.

The blue-chip 225-issue Nikkei stock average declined as much as 4.7% before closing down 4.2%, the biggest drop since the 12% crash on Aug. 5. The loss was led by chipmakers such as Disco after Nvidia extended losses in after-hours trading on news it received a subpoena from the U.S. Justice Department. The broader Topix lost 3.7%.

Resource-related stocks were pummeled by falling commodity prices, with trading house Mitsui & Co. declining 6% while poor U.S. manufacturing data hit shares of machine-makers such as Fanuc.