Daniel Loeb's hedge fund Third Point LLC is building a stake in Sony Corp. to push for changes, the second time in six years it has targeted the electronics maker, according to sources familiar with the matter.

Once a market leader in consumer electronics, Sony is now in the midst of a turnaround effort spearheaded by Kenichiro Yoshida, its chief executive who formerly served at its chief financial officer.

The maker of the iconic Walkman and Trinitron TV fell behind the likes of Apple Inc. in innovation after the release of the iPod in 2001 and the iPhone in 2007. Sony over the past decade has reinvented itself as an entertainment company with stable revenue from music content and its video game platform.