Tokyo stocks opened marginally lower Tuesday as investor consternation grew following British Prime Minister Theresa May postponing a crucial parliamentary vote, in favor of seeking more assurances from the European Union ahead of a now delayed vote on her Brexit plan.

As of 9:15 a.m., the 225-issue Nikkei Stock Average shed 21.82 points, or 0.10 percent, from Monday to 21,197.68.

The broader Topix index of all First Section issues on the Tokyo Stock Exchange, meanwhile, edged down 4.91 points, or 0.31 percent, to 1,584.90.

Oil and coal product, insurance, and machinery-linked issues comprised those that declined the most in the opening minutes after the morning break.