Shares of Sony Corp fell to their lowest in nearly four months on Friday after the electronics maker's new business strategy failed to convince investors it could deliver strong profit growth.

Sony, which is heading for its second straight annual loss, said on Thursday it would launch 3D TVs and networked products and services as part of a plan to boost its operating profit margin to 5 percent in the year to March 2013.

The 5 percent target had originally been set by CEO Howard Stringer in 2005 for the business year to March 2008.

It narrowly missed the target that year before falling into the red on the economic slowdown and tough competition.

Market players remain sceptical whether Sony can achieve its goal of turning its video game and TV operations profitable next year as it struggles to compete with overseas rivals such as South Korea's Samsung Electronics Co Ltd .

"What we're seeing is a weakening of Sony's brand power.

That's especially clear in North America where its market share has fallen sharply. The situation is so bad it almost makes me want to cover my eyes," said Chibagin Asset Management's advisor Fujio Ando.

"They no longer have products that are unique and can control the market," he said.

Shares of Sony were down 2.2 percent at 2,415 yen after earlier hitting 2,375 yen, their lowest since July 29. Thebenchmark Nikkei average was down 0.7 percent.

Sony said it was aiming for a 20 percent share in the global LCD TV market in unit terms in the year to March 2013. That compares with the 8.7 percent share it held in July-September, according to data from research firm Display Search.

In an effort to improve profits at its TV operations, Sony plans to have 40 percent of its LCD TVs assembled by outside manufacturers in the next business year starting April 2010, up from 20 percent this year.