Shares of Toyota Motor jumped 4.1 percent to 4,725 yen on Wednesday, hitting a 52-month high, after the automaker lifted its annual profit guidance, banking on stronger sales in its key U.S. market and a boost from a weaker yen.
It was the most traded stock on the main board by turnover.
The world's best-selling carmaker, which shipped a record number of cars last year, raised its net profit forecast for the year to March by more than 10 percent to 860 billion yen ($9.2 billion) on strong sales of the Camry sedan and other vehicles.
On Tuesday, it posted a net profit of 99.9 billion yen for the three months to Dec. 31, up 23.5 percent from a year ago when it struggled after natural disasters disrupted its supply chain.
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Its third-quarter profit figure was below the average estimate of 143.7 billion yen among seven analysts polled by Thomson Reuters.
Among Japan's big three automakers Toyota, Nissan Motor and Honda Motor, analysts see top seller Toyota as the most likely to benefit from a weakening yen because it has the highest ratio of production in Japan, more than half of which it exports.
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The yen is trading at around 92 to the dollar, compared with 78 at the start of October. The weaker the Japanese currency, the more money exporters make when they convert overseas profits back into yen.
In 2013, Toyota expects to sell 8.9 million vehicles globally. Across the group, which includes Daihatsu Motor and Hino Motors, it forecasts shipping 9.91 million vehicles.
Last year, the 75-year-old firm sold a record 8.72 million vehicles around the world. Its group-wide sales were also a record high of 9.75 million vehicles, beating General Motors to regain top rank among car manufacturers.
Shares in Toyota have risen nearly 50 percent since mid-November on hopes the weakening yen will boost its bottom line.