Sony Corp.'s first share sale in 26 years is fueling speculation the company may buy full control of Sony Financial Holdings Inc., a move that could save taxes and help the parent meet performance targets.

The company said on Tuesday it plans to raise about ¥440 billion ($3.6 billion) by selling common stock and convertible bonds. The announcement prompted a three-day, 11 percent jump in the life insurance unit's stock, while Sony said proceeds from the share sale will fund an increase in chip production.

Sony, which owns 60 percent of the insurance business, could save billions of dollars in taxes by taking complete control of the unit, according to Macquarie Group Ltd. Booking all of the net income generated by Sony Financial, the group's most profitable business, would also help reach the 10 percent return-on-equity target Chief Executive Officer Kazuo Hirai set for fiscal 2017.