TOKYO (Kyodo) -- The Nikkei stock index surged over 4 percent Friday after at one point recording its third-largest intraday point gain, as concerns over returns on massive investments in artificial intelligence eased following robust earnings from AI- and chip-related companies in Japan and the United States.

The 225-issue Nikkei Stock Average ended up 2,494.59 points, or 4.03 percent, from Thursday at 64,362.02. The broader Topix index finished 50.80 points, or 1.29 percent, higher at 4,003.30.

On the top-tier Prime Market, the main gainers were nonferrous metal, electric appliance, and glass and ceramics product issues.

The U.S. dollar rebounded, briefly strengthening to the upper 160 yen range in Tokyo after having dropped nearly 5 yen in New York overnight, prompting Japanese importers to buy the dollar to meet month-end demand.

At 5 p.m., the dollar fetched 160.20-22 yen compared with 159.42-52 yen in New York, where it briefly hit 157.97 yen, and 163.73-74 yen in Tokyo at 5 p.m. Thursday.

The euro was quoted at $1.1514-1515 and 184.46-50 yen against $1.1523-1533 and 183.69-79 yen in New York and $1.1436-1438 and 187.25-29 yen in Tokyo late Thursday afternoon.

The yield on the benchmark 10-year Japanese government bond ended at 2.795 percent, unchanged from Thursday's close.

The dollar sharply weakened to the upper 157 yen range within about 50 minutes on Thursday. A government source said Japanese authorities conducted currency intervention, a move that came after the yen had been trading around its weakest level in more than 39 years, and U.S. authorities reportedly conducted rate checks.

"The situation has made it easier to trigger dollar-buying and yen-selling on affordability and profit-taking," said Yuzo Sakai, chief manager of business planning at Ueda Totan Forex Ltd.

The benchmark Nikkei index briefly surged over 5 percent, or more than 3,400 points in the morning, lifted by AI- and semiconductor-related shares.

Gains were trimmed in the afternoon as investors locked in profits following the rapid rise.

Investor sentiment was buoyed after Microsoft Corp. reported better-than-expected earnings, while Tokyo Electron Ltd.'s solid earnings released after Thursday's close also supported buying.

"While volatility is expected to continue, the downside is likely to be limited as (the index) had approached the 60,000 line" earlier this week, said Masahiro Ichikawa, chief market strategist at Sumitomo Mitsui DS Asset Management Co.