Filing Details

Item 2 of the Schedule 13D is hereby amended to read in its entirety as follows:

This statement is being jointly filed by the following persons (the “Reporting Persons”):

Discovery Equity Partners, L.P. (“Discovery Equity Partners”) is an Illinois limited partnership primarily engaged in the business of investing in securities.

Discovery Group I, LLC (“Discovery Group”) is a Delaware limited liability company and a registered investment adviser under the Investment Advisers Act of 1940, as amended, that is primarily engaged in the business of investing in securities on behalf of institutional clients.

The business address of each of the Reporting Persons is 300 South Wacker Drive, Suite 600, Chicago, Illinois 60606.

During the past five years, neither of the Reporting Persons has been (i) convicted in a criminal proceeding (excluding traffic violations or similar misdemeanors) or (ii) a party to a civil proceeding of a judicial or administrative body of competent jurisdiction and as a result of such proceeding was or is subject to a judgment, decree or final order enjoining future violations of, or prohibiting or mandating activities subject to, federal or state securities laws, or finding any violation with respect to such laws.

Item 3 of the Schedule 13D is hereby amended to read in its entirety as follows:

The total purchase price for the 4,284,507 shares of Common Stock beneficially owned by the Reporting Persons as of May 10, 2017 was approximately $25,914,788. The source of such funds was the assets of Discovery Equity Partners, including proceeds of margin loans under margin loan facilities maintained in the ordinary course of business by Discovery Equity Partners with a broker on customary terms and conditions. Discovery Equity Partners is the legal owner of all of the Common Stock beneficially owned by Discovery Group.

Item 5 of the Schedule 13D is hereby amended to read in its entirety as follows:

The information concerning percentages of ownership set forth below is based on 52,840,074 shares of Common Stock outstanding as of April 28, 2017, as reported in the Company’s Quarterly Report on Form 10-Q for the quarter ended March 31, 2017.

Discovery Equity Partners beneficially owns 4,284,507 shares of Common Stock as of May 10, 2017, which represents 8.1% of the outstanding Common Stock.

Discovery Group beneficially owns 4,284,507 shares of Common Stock as of May 10, 2017, which represents 8.1% of the outstanding Common Stock.

Discovery Group is the investment manager of Discovery Equity Partners.   Discovery Group exercises ultimate voting and dispositive power of the securities held by Discovery Equity Partners. As a consequence, Discovery Group may be deemed to share beneficial ownership of all of the Common Shares owned by Discovery Equity Partners. Voting and disposition decisions at Discovery Group with respect to the investment of such securities are made by a five-person investment committee (the “Committee”) which makes such investment decisions by majority vote. No member of the Committee may act individually to vote or sell Common Shares held by Discovery Equity Partners, nor does any such member have a veto right concerning the vote or sale of any such common stock. Accordingly, no individual member of the Committee is deemed to beneficially own, and each individual member of the Committee expressly disclaims beneficial ownership of, within the meaning of Rule 13d-3, any Common Shares held by Discovery Equity Partners solely by virtue of the fact that he or she is a member of the Committee.

The transactions in Common Stock effected by the Reporting Persons during the past 60 days are set out in Exhibit 1 hereto.

No person other than Discovery Equity Partners is known to any Reporting Person to have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, any of the shares of Common Stock reported herein.

Item 6 of the Schedule 13D is hereby amended to read in its entirety as follows:

There are no contracts, arrangements, understandings or relationships (legal or otherwise) between or among any of the Reporting Persons and any other person with respect to any securities of the Company other than the governing documents of Discovery Group and Discovery Equity Partners, the margin loan facilities referred to under Item 3 above, the Joint Filing Agreements of the Reporting Persons with respect to the Schedule 13D that were included as exhibits thereto, the Joint Filing Agreement of the Reporting Persons with respect to this Amendment No. 4 included as Exhibit 2 to this Amendment No. 4, and the Power of Attorney granted by Michael R. Murphy with respect to reports under Section 13 of the Securities Exchange Act of 1934, as amended, which Power of Attorney is included as Exhibit 3 to this Amendment No. 4.

DISCOVERY EQUITY PARTNERS, L.P.

By: Michael R. Murphy*

DISCOVERY GROUP I, LLC

By: Michael R. Murphy*

Mark Buckley

Attorney-in-Fact for Michael R. Murphy

List of transactions effected by the Reporting Persons in the Company’s Common Stock during the 60-day period preceding this filing.