Tokyo ? Japan’s main stock market rose slightly at the open today after losing nearly 3 percent the day before in a session shortened due to massive selling caused by accounting probes of a popular Internet startup.

The benchmark Nikkei 225 index added 55.42 points, or 0.26 percent, to 15,396.60 points shortly after the open. The index dropped 464.77 points, or 2.9 percent, to close at 15,341.18 points, its biggest one-day drop since May 10, 2004.

The decline was triggered by massive selling – mainly targeting information and technology stocks – over allegations that Livedoor Co. had violated securities laws by giving false information.

It is headed by 33-year-old Takafumi Horie, who has risen to celebrity status as a geeky entrepreneur – a rarity in Japan.

The Tokyo Stock Exchange said it would delay the start of its afternoon session by 30 minutes, as planned. The bourse also said it would suspend trading if volume surged as much as on Wednesday.

The Nikkei dropped nearly 6 percent over the previous two days.

A woman walks past a video screen showing the current stock prices Wednesday in Tokyo. The Tokyo Stock Exchange rebounded slightly today after having to close 20 minutes early Wednesday because of massive selling.

The broader Topix index of all shares on the first section gained 1.93 points, or 0.12 percent, to 1,576.60 points early today. The Topix fell 56.94 points, or 3.49 percent, the day before.

As the market got flooded with orders Wednesday afternoon, the bourse issued a warning it would stop trading if the system capacity limit of 4 million transactions was reached. When it reached 3.5 million about an hour before the session’s close, it announced it would stop trading 20 minutes early.

Livedoor offers various Internet services, including consulting, telecommunications, mobile sites and software development. It also has bought up chunks of other companies and managed to raise money by offering more of its own stock – and it is this area that has drawn prosecutors’ scrutiny.

In currencies, the dollar was trading at 115.30 yen in Tokyo at 9 a.m., up 0.05 yen from late Wednesday in New York. The euro rose to $1.2107 from $1.2088 earlier in New York.