The president of Japan's largest company was taking calls from irate shareholders Thursday morning as the price of its stock fell by more than $500 a share.

Like the heads of many other Japanese companies, Haruo Yamaguchi, chief executive of telecommunications giant Nippon Telegraph and Telephone Corp., was struggling to find an explanation for the dive."NTT's performance has not weakened at all. We can't avoid drifting with the general current," Yamaguchi told reporters. NTT stock - Japan's most expensive - fell $516 a share this morning but recovered slightly in the afternoon, closing at $6,903, a loss of $452 or 6.1 percent for the day.

The Tokyo Stock Exchange's leading index fell 1,836.05 points, or 5.96 percent, in the morning but that loss declined to 963.85 points, or 3.13 percent, by the day's end.

"We are making the utmost efforts to raise the price," Yamaguchi said. NTT's stock was first offered to the public at $7,742 a share in February 1987, two years after the former telecommunications monopoly was turned into a private company. It had the largest stock market valuation in the world.

He said NTT plans to seek approval at its stockholders meeting in June to raise the dividend from $32.25 to $38.70, or from 10 percent to 12 percent of one share's face value of $322.50.

Yamaguchi said he owns 10 shares, and that he and other company directors are not permitted to sell their shares.

On the first day NTT stock was listed on the Tokyo exchange in 1987, there were 1.28 million buy orders for the 10,000 shares then offered. Two months later, NTT was trading at $20,516 a share.

Most Japanese share prices are in the $6 to $13 range.

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(Additional information)

Tokyo market, yen fall sharply

The Tokyo Stock Exchange fell 3.13 percent Thursday, three days after the third-worst drop in its history, and the yen fell sharply against the dollar. The 225-share Nikkei Stock Average fell 963.85 points, ending a hectic day at 29,843.34, its lowest closing since Dec. 24, 1988. Thursday's drop put the Nikkei's losses so far this year at 23 percent, or 9,072.53 points.