TOKYO - Japan's Nikkei share average rose above 43,000 for the first time on Wednesday, with the broader Topix index also marking a fresh all-time high, tracking Wall Street's overnight gains and extending the rally into a sixth straight session.

The Nikkei gained as much as 1.4 percent by 0140 GMT to touch a record 43,309.62 and extend its winning run to 7.5 percent since Aug 4. Monday of this week was a national holiday in Japan.

The broader Topix advanced 1 percent to an unprecedented 3,097.94, also rising for the sixth straight session.

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Overnight, the S&P 500 and Nasdaq closed at record highs as a moderate reading of July inflation bolstered bets for a Federal Reserve interest rate cut next month.

"A sense of relief is permeating through markets" following the US Consumer Price Index (CPI) data, leading Japanese stocks "to take a step higher," said Maki Sawada, an equities strategist at Nomura Securities.

At the same time, "there are signs that the Nikkei is overheated after its extremely steep rally, and a steep drop at any time wouldn't come as any surprise," she added.

The Nikkei's relative strength index (RSI) rose above 75, well beyond the 70 line that many analysts consider indicative of an overheated market. The RSI was at a similar level on July 24, and the Nikkei fell in the following four sessions.

A stronger yen exchange rate, after Fed easing expectations hurt the dollar, also limited Japanese stock gains in the latest session, Sawada said.

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A strong yen reduces the value of overseas revenues at Japan's heavyweight exporters.

Of the Nikkei's 225 components, 183 rose, 41 fell and one traded flat.

Tech shares stood out, with chipmaker Renesas Electronics jumping more than 7 percent, chip-testing equipment maker Advantest rising more than 2 percent and Sony Group gaining 4.6 percent.