Shares in Sony Corp <6758.T> lost nearly 6 percent on Monday as investors shrugged off the electronics maker's upward revision to its earnings forecast and sold on worries over the U.S. market and a stronger yen.

Sony posted its fourth consecutive quarterly loss on Friday but cut its annual operating loss forecast by 45 percent to 60 billion yen ($669 million) on cost-cutting.

Panasonic Corp <6752.T>, which vies with Sony for the title of the world's largest consumer electronics maker, also cited cost-cutting in lifting its annual operating profit estimate on Friday by 60 percent to 120 billion yen.

Sony's shares lost 5.8 percent to 2,625 yen by the end of the morning, far worse than the Nikkei average, which fell 2.7 percent, and Panasonic's loss of 1.6 percent. The steeper fall in Sony's stock reflects its heavy exposure to the U.S. market and a stronger yen.

This is pretty much because of forex and a tumble in New York, said Mizuho Securities analyst Ryosuke Katsura.

If it were not for what happened to the yen and Wall Street, Sony shares could very well have gained ground.

The yen rose to two-week highs on Monday, while the Dow Jones industrial average <.DJI> suffered its worst slide since July on Friday, triggering a tumble in Japanese stocks as well.

Sony earns 70 percent of its revenues overseas, making its bottom line susceptible to a stronger yen. By comparison Panasonic makes more than half of its sales in Japan.

Sony also has insurance and banking operations, leaving its earnings more vulnerable to swings in the financial markets.

(Reporting by Kiyoshi Takenaka; Editing by Michael Watson)