TOKYO (Kyodo) -- The Nikkei stock index dropped Monday morning, weighed down by selling of artificial intelligence- and chip-related shares as hopes for stronger demand waned after top executives of major U.S. AI developers called for a slowdown of development.

The 225-issue Nikkei Stock Average fell 512.73 points, or 0.80 percent, from Friday to 63,498.61, after briefly slipping to its lowest level since Aug. 4. The broader Topix index was up 26.59 points, or 0.66 percent, at 4,054.89.

The U.S. dollar remained weak, moving mostly in the upper 153 yen range in Tokyo, as speculation remained strong that the Bank of Japan will accelerate its pace of rate hikes, dealers said.

At noon, the dollar fetched 154.05-06 yen compared with 153.53-63 yen in New York and 154.21-23 yen in Tokyo at 5 p.m. Friday.

The euro was quoted at $1.1581-1582 and 178.41-42 yen against $1.1592-1602 and 178.07-17 yen in New York and $1.1605-1606 and 178.97-179.01 yen in Tokyo late Friday afternoon.

The benchmark Nikkei index briefly lost more than 1,200 points on weak AI and semiconductor shares after Anthropic CEO Dario Amodei called on his website Saturday for the pace of AI development to slow down across the industry and OpenAI CEO Sam Altman said he was also considering slowing development.

SoftBank Group led declines after a report said OpenAI, in which it has invested, will not go public this year, analysts said. The Japanese company ended the morning down 10.6 percent at 5,846 yen.

Meanwhile, the market was supported by buying following recent declines as well as firm bank and other financial issues that were sought on hopes that further rate hikes by the Japanese central bank will boost profits.