TOKYO (Kyodo) -- Tokyo stocks rose Tuesday morning, as a weaker yen boosted exporters, while major trading firms gained on news that U.S. investor Warren Buffett's company has raised its stakes in them.

The 225-issue Nikkei Stock Average gained 546.71 points, or 1.46 percent, from Monday to 37,943.23. The broader Topix index was up 39.66 points, or 1.44 percent, at 2,787.78.

The U.S. dollar climbed to the upper 149 yen range, with the Japanese currency coming under selling pressure as traders expect the Bank of Japan will not raise interest rates at its two-day policy meeting through Wednesday, dealers said.

At noon, the dollar fetched 149.67-68 yen compared with 149.15-25 yen in New York and 148.85-88 yen in Tokyo at 5 p.m. Monday.

The euro was quoted at $1.0908-0909 and 163.26-30 yen against $1.0916-0926 and 162.96-163.06 yen in New York and $1.0875-0876 and 161.89-93 yen in Tokyo late Monday afternoon.

The Nikkei index briefly traded above 38,000 for the first time since February, as tech stocks tracked their U.S. counterparts. Export-oriented auto issues were lifted by a weaker yen, which boosts exporters' overseas profits when repatriated.

Major trading house issues were in strong demand after financial statements showed billionaire investor Buffett's Berkshire Hathaway Inc. had raised its stakes in the companies.