(10) Stockholders’ Equity

Common Stock. Since the inception of our share repurchase programs and through September 30, 2017, we have repurchased a total of 41.1 million shares at a cost of $1.5 billion. Shares that are repurchased are classified as treasury stock pending future use and reduce the number of shares outstanding used in calculating earnings per share. We temporarily suspended our share repurchase program due to recent acquisitions. Accordingly, we did not repurchase any shares during the three months ended September 30, 2017 or September 30, 2016. There is no expiration date for this program, and the program may be accelerated, suspended, delayed or discontinued at any time at the discretion of our board of directors. At September 30, 2017, 13.6 million additional shares can be repurchased under the approved share repurchase program.

Preferred Stock. In April 1997, the board of directors designated 2.0 million shares of our $0.01 par value preferred stock as Series A Junior Participating Preferred Stock. No shares were issued or outstanding at September 30, 2017 and June 30, 2017.

Stock Options and Restricted Stock Units. We have granted stock options and restricted stock units to personnel, including officers and directors, in accordance with the ResMed Inc. 2009 Incentive Award Plan (the “2009 Plan”). The options have expiration dates of seven years from the date of grant and the options and restricted stock units vest over one to four years. The maximum number of shares of our common stock authorized for issuance under the 2009 Plan is 43.7 million shares. The number of securities remaining available for future issuance under the 2009 Plan at September 30, 2017 is 11.6 million.

The following table summarizes option activity during the three months ended September 30, 2017:


	Options		Weighted Average Exercise Price		Weighted Average Remaining Contractual Term in Years
Outstanding at beginning of period		1,495,573	$	47.09	3.9
Granted		-		-
Exercised		(147,675)		31.70
Forfeited		-		-
Outstanding at end of period		1,347,898	$	48.78	3.9
Exercise price of granted options	$	-
Options exercisable at end of period		820,348	$	43.05

The following table summarizes the activity of restricted stock units during the three months ended September 30, 2017:


	Restricted Stock Units		Weighted Average Grant-Date Fair Value		Weighted Average Remaining Contractual Term in Years
Outstanding at beginning of period		1,906,394	$	53.26	1.6
Granted		4,851		72.15
Vested		(3,232)		52.22
Expired		(8,395)		52.70
Forfeited		(4,212)		52.70
Outstanding at end of period		1,895,406	$	53.31	1.3

Employee Stock Purchase Plan (the “ESPP”). Under the ESPP, we offer participants the right to purchase shares of our common stock at a discount during successive offering periods. At September 30, 2017, the number of shares remaining available for future issuance under the ESPP is 0.8 million shares.