Tokyo: Japan’s Nikkei stock average climbed 2.4% on Friday, its biggest one-day percentage gain in over three weeks, as Canon Inc. and other exporters rose after surprisingly strong US GDP data temporarily eased fears about its economic health.

Banks climbed as well, with top lender Mitsubishi UFJ Financial Group and its peers rising after US banks gained on the brighter economic outlook and a management shake-up at top mortgage financial company Fannie Mae.

But Fujifilm Holdings plunged 12.4%, its biggest one day loss in 21 years, after the company slashed its profit forecast by almost a quarter due to higher raw materials costs and a sharp price fall for digital cameras.

The Nikkei rose 3.2% on the week but slid 2.3% for the month, its third consecutive month in negative territory. Market players were sceptical about Friday’s gains.

“Yes, the US GDP figures were good, but this is old data, as of the end of June,” said Masayoshi Okamoto, head of dealing at Jujiya Securities.

“The Nikkei has responded strongly but we can’t say it’s gained on reasons that are sustainable. Everything could easily be erased next week.”

Others pointed out that fund managers were buying shares to increase the value of their positions before closing books for the month.

“What we’re really seeing here is month-end window-dressing,” said Hideyuki Ishiguro in the investment strategy department of Okasan Securities.

The benchmark Nikkei gained 304.62 points to 13,072.87 and marked its greatest one-day percentage gain since 6 August.

The broader Topix rose 2.9% to 1,254.71.