(Updates to midafternoon)

TOKYO, Jan 13 (Reuters) - Japan's Nikkei average dropped 4.3 percent on Tuesday as a stronger yen pressured Toyota Motor (7203.T: Quote, Profile, Research) and other exporters, with worry about earnings losses at major companies reinforcing fears about the global economy.

Sony Corp (6758.T: Quote, Profile, Research) tumbled more than 8 percent after a source said the firm was expected to post an operating loss of about 100 billion yen ($1.1 billion) for 2008/09, far short of the company's forecast for a profit of 200 billion yen. [ID:nT345549]

Toshiba Corp (6502.T: Quote, Profile, Research) slid after the Nikkei business daily said the electronics maker was expected to report an operating loss of about 200 billion yen for the year ending in March. [ID:nTFA003246]

"These worsening forecasts aren't just a Japanese event, we're seeing the same thing happen in the United States, and it's pushing the dollar lower against the yen," said Masayoshi Okamoto, head of dealing at Okasan Securities.

"Though stock markets rallied briefly around the end and beginning of the year, it's clear now that the worsening of the real global economy is far outweighing expectations for the new U.S. administration."

The dollar slipped close to its day's low, fetching around 89.27 yen and heading back towards the three-week low of 88.89 yen hit on Monday, which itself was not far from December's 13-½ year trough just above 87 yen.

The benchmark Nikkei .N225 lost 381.56 points to 8,456.13 after earlier falling to 8,405.50, its lowest point in a month, and appeared on target for its lowest close in a month as well.

The broader Topix .TOPX shed 4.4 percent to 817.17.