17.

Stock-based compensation plans

The stock-based compensation expense for the fiscal years ended March 31, 2017, 2018 and 2019 was 2,737 million yen, 5,249 million yen and 5,499 million yen, respectively. The total cash received from exercises under all of the stock-based compensation plans during the fiscal years ended March 31, 2017, 2018 and 2019 was 2,730 million yen, 7,129 million yen and 12,757 million yen, respectively. Sony issued new shares upon exercise of these rights.

Sony has a stock-based compensation incentive plan for selected directors, corporate executive officers and employees in the form of a stock acquisition rights plan. The stock acquisition rights generally have three year graded vesting schedules and are exercisable up to ten years from the date of grant.

The weighted-average fair value per share at the date of grant of stock acquisition rights granted during the fiscal years ended March 31, 2017, 2018 and 2019 was 1,291 yen, 2,045 yen and 1,593 yen, respectively. The fair value of stock acquisition rights granted on the date of grant and used to recognize compensation expense for the fiscal years ended March 31, 2017, 2018 and 2019 was estimated using the Black-Scholes option-pricing model with the following weighted-average assumptions:


	Fiscal year ended March 31
	2017			2018			2019
Weighted-average assumptions
Risk-free interest rate		1.10	%		1.14	%		1.37	%
Expected lives		6.83	years		6.55	years		5.98	years
Expected volatility^*		40.00	%		38.49	%		32.52	%
Expected dividends		0.66	%		0.40	%		0.35	%

Expected volatility was based on the historical volatilities of Sony Corporation’s common stock over the expected life of the stock acquisition rights.

A summary of the activities regarding the stock acquisition rights plan during the fiscal year ended March 31, 2019 is as follows:


	Fiscal year ended March 31, 2019
	Number of shares		Weighted- average exercise price		Weighted- average remaining life		Total intrinsic value
			Yen		Years		Yen in millions
Outstanding at beginning of the fiscal year		14,005,900		3,017
Granted		2,907,300		5,108
Exercised		4,525,300		2,819
Forfeited or expired		174,000		3,862

Outstanding at end of the fiscal year		12,213,900		3,665		7.46		11,133

Exercisable at end of the fiscal year		5,820,800		2,855		5.84		9,867

The total intrinsic value of shares exercised under the stock acquisition rights plan during the fiscal years ended March 31, 2017, 2018 and 2019 was 1,541 million yen, 6,970 million yen and 13,325 million yen, respectively.

As of March 31, 2019, there was 5,159 million yen of total unrecognized compensation expense related to nonvested stock acquisition rights. This expense is expected to be recognized over a weighted-average period of 1.94 years.