June 26 (Bloomberg) -- Sony Corp., the world's second- largest consumer-electronics maker, pledged to raise its return on equity to 10 percent in three years, bringing profitability closer to levels at Samsung Electronics Co. and Nintendo Co.

The target, or profit divided by book value, announced today is almost double the 5.8 percent average for Tokyo-based Sony in the past five years, based on data compiled by Bloomberg. Samsung had an average return of 21.8 percent and Nintendo 9.6 percent.

Chairman Howard Stringer said Sony will expand in emerging markets and invest 1.8 trillion yen ($16.7 billion) during the three years to March 2011 on new technology and business expansion. The inventor of the Walkman also said it plans to cut the costs of making TVs and game consoles to boost profit.

``Sony will lose its place as a global leader if its ROE stays lower than 10 percent,'' Mitsushige Akino, who manages $557 million at Ichiyoshi Investment Management Co. in Tokyo, said by telephone. ``Its ROE looks very poor compared with overseas rivals such as Samsung.''

Sony shares climbed 2.9 percent to close at 5,060 yen, before the company's announcement.

Stringer, who failed to meet the company's last target to earn 5 cents for every dollar of sales, reiterated that goal for this fiscal year.

A 5 percent operating margin is ``the base line, the minimum acceptable level,'' Stringer said at a briefing in Tokyo. ``We have been trying to restore profitability. The work is not completed.''

Sony aims to double its revenue from electronics in Brazil, Russia, India and China within three years by bolstering sales in seven main businesses, including Bravia televisions and Blu-ray disc players. Overall sales in the so-called BRIC nations will double to 2 trillion yen during the period, it said.

To contact the reporters on this story: Hiroshi Suzuki in Tokyo at Hsuzuki5@bloomberg.net; Masaki Kondo in Tokyo at mkondo3@bloomberg.net. Last Updated: June 26, 2008 04:31 EDT