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UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13D

 

 

 

CUSIP No. 141619106
	1.	Names of Reporting Persons. Discovery Equity Partners, L.P.
	2.	Check the Appropriate Box if a Member of a Group (See Instructions)
		(a)			o
		(b)			o
	3.	SEC Use Only
	4.	Source of Funds (See Instructions) WC
	5.	Check if Disclosure of Legal Proceedings Is Required Pursuant to Items 2(d) or 2(e)     o
	6.	Citizenship or Place of Organization Illinois
Number of Shares Beneficially Owned by Each Reporting Person With			7.	Sole Voting Power None.
			8.	Shared Voting Power 1,006,537
			9.	Sole Dispositive Power None.
			10.	Shared Dispositive Power 1,006,537
	11.	Aggregate Amount Beneficially Owned by Each Reporting Person 1,006,537
	12.	Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions)   o
	13.	Percent of Class Represented by Amount in Row (11) 6.2%
	14.	Type of Reporting Person (See Instructions) PN

CUSIP No.  141619106
	1.	Names of Reporting Persons. Discovery Group I, LLC
	2.	Check the Appropriate Box if a Member of a Group (See Instructions)
		(a)			o
		(b)			o
	3.	SEC Use Only
	4.	Source of Funds (See Instructions) AF
	5.	Check if Disclosure of Legal Proceedings Is Required Pursuant to Items 2(d) or 2(e)     o
	6.	Citizenship or Place of Organization Delaware
Number of Shares Beneficially Owned by Each Reporting Person With			7.	Sole Voting Power None.
			8.	Shared Voting Power 1,149,751
			9.	Sole Dispositive Power None.
			10.	Shared Dispositive Power 1,149,751
	11.	Aggregate Amount Beneficially Owned by Each Reporting Person 1,149,751
	12.	Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions)   o
	13.	Percent of Class Represented by Amount in Row (11) 7.0%
	14.	Type of Reporting Person (See Instructions) IA

CUSIP No.  141619106
	1.	Names of Reporting Persons. Daniel J. Donoghue
	2.	Check the Appropriate Box if a Member of a Group (See Instructions)
		(a)			o
		(b)			o
	3.	SEC Use Only
	4.	Source of Funds (See Instructions) AF
	5.	Check if Disclosure of Legal Proceedings Is Required Pursuant to Items 2(d) or 2(e)     o
	6.	Citizenship or Place of Organization United States of America
Number of Shares Beneficially Owned by Each Reporting Person With			7.	Sole Voting Power None.
			8.	Shared Voting Power 1,149,751
			9.	Sole Dispositive Power None.
			10.	Shared Dispositive Power 1,149,751
	11.	Aggregate Amount Beneficially Owned by Each Reporting Person 1,149,751
	12.	Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions)   o
	13.	Percent of Class Represented by Amount in Row (11) 7.0%
	14.	Type of Reporting Person (See Instructions) IN

CUSIP No.  141619106
	1.	Names of Reporting Persons. Michael R. Murphy
	2.	Check the Appropriate Box if a Member of a Group (See Instructions)
		(a)			o
		(b)			o
	3.	SEC Use Only
	4.	Source of Funds (See Instructions) AF
	5.	Check if Disclosure of Legal Proceedings Is Required Pursuant to Items 2(d) or 2(e)     o
	6.	Citizenship or Place of Organization United States of America
Number of Shares Beneficially Owned by Each Reporting Person With			7.	Sole Voting Power None.
			8.	Shared Voting Power 1,149,751
			9.	Sole Dispositive Power None.
			10.	Shared Dispositive Power 1,149,751
	11.	Aggregate Amount Beneficially Owned by Each Reporting Person 1,149,751
	12.	Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions)   o
	13.	Percent of Class Represented by Amount in Row (11) 7.0%
	14.	Type of Reporting Person (See Instructions) IN

 

 

 

Item 1.		Security and Issuer
		This statement relates to the Common Stock, $0.001 par value per share (the “Common Stock”), of Cardiovascular Systems, Inc., a Delaware corporation (the “Company”), which has its principal executive offices at 651 Campus Drive St. Paul, Minnesota 55112.  This Amendment No. 1 amends and supplements, as set forth below, the information contained in items 1, 3, 5 and 6 of the Schedule 13D filed by the Reporting Persons with respect to the Company on August 17, 2011 (as so amended, the “Schedule 13D”).  All capitalized terms used herein but not defined herein have the meanings set forth in the Schedule 13D.  Except as amended by this Amendment No. 1, all information contained in the Schedule 13D is, after reasonable inquiry and to the best of the Reporting Persons’ knowledge and belief, true, complete and correct as of the date of this Amendment No. 1.
Item 3.		Source and Amount of Funds or Other Consideration
		Item 3 of the Schedule 13D is hereby amended to read in its entirety as follows:   The total purchase price for the 1,149,751 shares of Common Stock beneficially owned by Discovery Group and Messrs. Donoghue and Murphy as of August 28, 2011 was approximately $15,693,268, and the total purchase price for the 1,006,537 shares of Common Stock beneficially owned by Discovery Equity Partners was approximately $13,738,826.  The source of such funds was the assets of Discovery Equity Partners and another private investment partnership (collectively, the “Partnerships”) over which Discovery Group exercises discretionary investment management authority, including proceeds of margin loans under margin loan facilities maintained in the ordinary course of business by the Partnerships with a broker on customary terms and conditions.  The Partnerships are the legal owner of all of the Common Stock beneficially owned by Discovery Group and Messrs. Donoghue and Murphy.
Item 5.		Interest in Securities of the Issuer
		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 16,350,698 shares of Common Stock reported outstanding as of May 31, 2011 in the Company’s Registration Statement of Form S-3, filed on June 3, 2011.   Discovery Equity Partners beneficially owns 1,006,537 shares of Common Stock as of August 28, 2011, which represents 6.2% of the outstanding Common Stock.   Discovery Group beneficially owns 1,149,751 shares of Common Stock as of August 28, 2011, which represents 7.0% of the outstanding Common Stock.   Mr. Donoghue beneficially owns 1,149,751 shares of Common Stock as of August 28, 2011, which represents 7.0% of the outstanding Common Stock.   Mr. Murphy beneficially owns 1,149,751 shares of Common Stock as of August 28, 2011, which represents 7.0% of the outstanding Common Stock.   Discovery Group is the sole general partner of Discovery Equity Partners and has sole discretionary investment authority with respect to the other Partnership’s investment in the Common Stock.  Messrs. Donoghue and Murphy are the sole managing members of Discovery Group.  As a consequence, Discovery Group and Messrs. Donoghue and Murphy may be deemed to share beneficial ownership of all of the shares of Common Stock owned by both of the Partnerships, while Discovery Equity Partners shares beneficial ownership with Discovery Group and Messrs. Donoghue and Murphy of only the shares of Common Stock owned by it.
		The transactions in Common Stock effected by the Reporting Persons since the date of the most recent filing on Schedule 13D are set out in Exhibit 1 hereto.   No person other than the Partnerships 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.		Contracts, Arrangements, Understandings or Relationships with Respect to Securities of the Issuer
		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 the Partnerships, the margin loan facilities referred to under Item 3 of the Schedule 13D, the Joint Filing Agreement of the Reporting Persons with respect to the Schedule 13D that was included as an exhibit thereto, the Joint Filing Agreement of the Reporting Persons with respect to this Amendment No. 1 included as Exhibit 2 to this Amendment No. 1, and the Powers of Attorney granted by Messrs Donoghue and Murphy with respect to reports under Section 13 of the Securities Exchange Act of 1934, as amended, which Powers of Attorney are included as Exhibit 3 and Exhibit 4, respectively, to this Amendment No. 1.

Item 7.	Material to Be Filed as Exhibits
	Exhibit 1:       List of transactions by Reporting Persons in the Company’s Common Stock since the date of the most recent filing on Schedule 13D.
	Exhibit 2:       Joint Filing Agreement dated as of August 29, 2011, by and among Discovery Equity Partners; Discovery Group; Daniel J. Donoghue; and Michael R. Murphy.
	Exhibit 3:       Power of Attorney of Daniel J. Donoghue, dated as of April 28, 2008.
	Exhibit 4:       Power of Attorney of Michael R. Murphy, dated as of April 28, 2008.

 

 

 

 

	August 29, 2011
	Date
	DISCOVERY GROUP I, LLC, for itself and as general partner of DISCOVERY EQUITY PARTNERS, L.P.     By:  Michael R. Murphy*
	Signature
	Michael R. Murphy, Managing Member
	Name/Title
	Daniel J. Donoghue*
	Signature
	Daniel J. Donoghue
	Name/Title
	Michael R. Murphy*
	Signature
	Michael R. Murphy
	Name/Title
	*By: /s/ Mark Buckley
	Mark Buckley Attorney-in-Fact for Daniel J. Donoghue Attorney-in-Fact for Michael R. Murphy

 

 

Exhibit 1	List of transactions by Reporting Persons in the Company’s Common Stock since the date of the most recent filing on Schedule 13D.
Exhibit 2	Joint Filing Agreement dated as of August 29, 2011, by and among Discovery Equity Partners; Discovery Group; Daniel J. Donoghue; and Michael R. Murphy.
Exhibit 3	Power of Attorney of Daniel J. Donoghue, dated as of April 28, 2008.
Exhibit 4	Power of Attorney of Michael R. Murphy, dated as of April 28, 2008.

 

 

 

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Date		Type		Price		Shares
8/17/20111		Purchase		$13.5874		20063
8/18/20112		Purchase		12.8367		19025
8/19/20113		Purchase		12.5073		26653
8/22/20114		Purchase		12.2850		15707
8/23/20115		Purchase		13.0664		14886
8/24/20116		Purchase		13.5434		34464
8/25/20117		Purchase		13.3633		14947
8/26/20118		Purchase		13.7814		17481

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