15.	STOCKHOLDERS' EQUITY

The following is a summary of our capital stock activity over the past three years:

	Number of Shares
	Common Stock		Treasury Stock
September 30, 2015		33,489,181		9,041,678
Exercise of stock options		606,562
Restricted stock under EIP and OIP, net of forfeitures		86,277
Restricted stock under Deposit Share Program, net of forfeitures		1,847
Common stock under ESPP		77,437
Repurchases of common stock under share repurchase plans				636,839
Repurchases of common stock – other				66,125

September 30, 2016		34,261,304		9,744,642
Exercise of stock options		818,640
Restricted stock under OIP, net of forfeitures		81,047
Common stock under ESPP		69,751
Repurchases of common stock under share repurchase plans				167,809
Repurchases of common stock – other				35,739

September 30, 2017		35,230,742		9,948,190
Exercise of stock options		487,915
Restricted stock under OIP, net of forfeitures		93,817
Common stock under ESPP		49,991
Repurchases of common stock under share repurchase plans				369,791
Repurchases of common stock – other				38,166

September 30, 2018		35,862,465		10,356,147

COMMON STOCK

Each share of common stock, including those awarded as restricted stock, but not restricted stock units, entitles the holder to one vote on all matters submitted to a vote of Cabot Microelectronics' stockholders. Common stockholders are entitled to receive ratably the dividends, if any, as may be declared by the Board of Directors. Holders of restricted stock units awarded as of fiscal 2016 are entitled to dividend equivalents, which are paid to the holder upon the vesting of the restricted stock units. The number of authorized shares of common stock is 200,000,000 shares.

SHARE REPURCHASES

In January 2016, our Board of Directors authorized an increase in the amount available under our share repurchase program from $75,000 to $150,000. Under this program, we repurchased 369,791 shares for $40,726 during fiscal 2018, 167,809 shares for $12,035 during fiscal 2017, and 636,839 shares for $25,980 during fiscal 2016. As of September 30, 2018, $81,271 remains available under our share repurchase program. To date, we have funded share repurchases under our share repurchase program from our existing cash balance, and anticipate we will continue to do so. The program, which became effective on the authorization date, may be suspended or terminated at any time, at the Company's discretion. For additional information on share repurchases, see Part II, Item 5, "Market for Registrant's Common Equity, Related Stockholder Matters and Issuer Purchases of Equity Securities" and the section titled "Liquidity and Capital Resources" in Part II, Item 7, "Management's Discussion and Analysis of Financial Condition and Results of Operations" of this Form 10-K.

Separate from this share repurchase program, a total of 38,166, 35,739 and 66,125 shares were purchased during fiscal 2018, 2017 and 2016, respectively, pursuant to the terms of our OIP as shares withheld from award recipients to cover payroll taxes on the vesting of shares of restricted stock granted under the OIP.