Japan's Nikkei struggles for momentum as tariff deadline looms

By Brigid Riley

TOKYO, March 24 (Reuters) - Japan's Nikkei share average was flat at the morning session's close on Monday as a modest rise in Wall Street's three main indexes last week marginally boosted market sentiment, but a looming deadline for implementing additional U.S. tariffs kept investors cautious.

The Nikkei .N225 was unchanged from Friday's close of 37,676.97 by the midday break, while the broader Topix .TOPX fell 0.3% to 2,794.67 after logging an eight-month peak at the end of last week.

The Nikkei received some support as a portion of heavyweight shares saw some buying. Uniqlo parent firm Fast Retailing 9983.T rose 0.4% and AI-focused startup investor SoftBank Group 9984.T climbed 2.9%.

However, the benchmark index struggled to advance, seesawing between gains and losses as market participants eyed the April 2 deadline that U.S. President Donald Trump has set for reciprocal and sector-specific tariffs to go into effect.

Trump hinted that he would be flexible regarding the new round of levies, helping lift the S&P and Dow at the end of the week, but Japanese equity investors on Monday took a wary approach to the impending threat. .N

Many important details regarding the latest tariffs are still unknown, keeping investors on edge, said Kazuo Kamitani, a strategist at Nomura Securities. "There's no way to predict it, so we have no choice but to wait for the announcement," he said.

Many major semiconductor-related shares dragged on Monday to follow their U.S. peers after the Philadelphia SE Semiconductor Index .SOX ended nearly 1% down on Friday.

Tokyo Electron 8035.T slid 0.3%, while Screen Holdings 7735.T stumbled 3.3% to become the biggest percentage loser on the Nikkei.

Among other big-name shares, Seven & i Holdings 3382.T rose 2% and Chugai Pharmaceutical 4519.T climbed 1.6%. Robot maker Fanuc 6954.T gave up 1.7%.

Of the Nikkei's 225 constituents, 66 advanced while157declined. Two shares were untraded.