TOKYO, Aug 2 (Reuters) - Japanese shares fell on Wednesday dragged down by heavyweight chip-related shares, as investors awaited overseas market reaction to a cut on the U.S. credit rating by Fitch rating agency.

The Nikkei index fell 1.84% to 32,861.29 by the midday break.

"Japan's chip-related stocks tracked declines in the Nasdaq, which weighed on Japanese shares," said Masahiro Ichikawa, chief market strategist at Sumitomo Mitsui DS Asset Management.

"And investors were cautions after the Fitch rating cut the U.S. credit rating. They awaited the reaction of the U.S. market later in the day."

Rating agency Fitch on Tuesday downgraded the U.S. to AA+ from AAA in a move that drew an angry response from the White House and surprised investors, coming despite the resolution two months ago of the debt ceiling crisis.

Chip-making equipment maker Tokyo Electron slipped 3.11% to and chip-testing equipment maker Advantest lost 4.21%.

Shares in Nomura Holdings tanked 7.5% even as the nation's top brokerage reported a jump in first-quarter net profit.

Its losses sent the brokerage sector down 3.85% to make it one of the worst performers among the 33 industry sub-indexes on the Tokyo Stock Exchange.

The insurance sector lost 3.87%.

The broader Topix fell 1% to 2,314.03. The losses were capped shares in Toyota Motor, which rose 3% after the automaker nearly doubled its operating profit in the first quarter.

Komatsu, the world's second-largest construction machinery maker, rose 0.99% after its bigger rival Caterpillar surged nearly 9% overnight after reporting a rise in second-quarter profit.

(Reporting by Junko Fujita; Editing by Rashmi Aich)