SEC FORM 3

SEC Form 3

FORM 3

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person^*

Burbank Jeffrey H

(Last)

(First)

(Middle)

C/O NXSTAGE MEDICAL, INC.

439 SOUTH UNION STREET, 5TH FLOOR

(Street)

LAWRENCE

01843

(City)

(State)

(Zip)

2. Date of Event Requiring Statement (Month/Day/Year)
10/27/2005

3. Issuer Name and Ticker or Trading Symbol
NxStage Medical, Inc. [ NXTM ]

4. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

X	Director	10% Owner
X	Officer (give title below)	Other (specify below)
	President & CEO

5. If Amendment, Date of Original Filed (Month/Day/Year)

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Beneficially Owned
1. Title of Security (Instr. 4)	2. Amount of Securities Beneficially Owned (Instr. 4)	3. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	4. Nature of Indirect Beneficial Ownership (Instr. 5)
Common Stock	437,555⁽¹⁾	D

Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 4)	2. Date Exercisable and Expiration Date (Month/Day/Year)		3. Title and Amount of Securities Underlying Derivative Security (Instr. 4)		4. Conversion or Exercise Price of Derivative Security	5. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	6. Nature of Indirect Beneficial Ownership (Instr. 5)
1. Title of Derivative Security (Instr. 4)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares	4. Conversion or Exercise Price of Derivative Security	5. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	6. Nature of Indirect Beneficial Ownership (Instr. 5)
Stock Option (right to buy)	01/15/2001⁽²⁾	01/14/2011	Common Stock	54,840⁽³⁾	$3.76⁽³⁾	D
Stock Option (right to buy)	08/22/2001⁽²⁾	08/21/2011	Common Stock	54,840⁽³⁾	$3.76⁽³⁾	D
Stock Option (right to buy)	03/07/2002⁽⁴⁾	03/06/2012	Common Stock	36,560⁽³⁾	$4.1⁽³⁾	D
Stock Option (right to buy)	02/04/2003⁽²⁾	02/03/2013	Common Stock	36,560⁽³⁾	$4.1⁽³⁾	D
Stock Option (right to buy)	01/20/2005⁽²⁾	01/20/2015	Common Stock	73,120⁽³⁾	$6.84⁽³⁾	D
Stock Option (right to buy)	09/15/2006⁽⁵⁾	09/15/2012	Common Stock	146,240⁽³⁾	$8.54⁽³⁾	D
Series B Convertible Preferred Stock	⁽⁶⁾	⁽⁷⁾	Common Stock	54,771⁽⁸⁾	⁽⁸⁾	D
Stock Option (right to buy)	02/13/2004⁽²⁾	02/12/2014	Common Stock	44,603⁽³⁾	$5.47⁽³⁾	D
Stock Option (right to buy)	11/01/1998⁽²⁾	11/01/2008	Common Stock	14,146⁽³⁾	$0.34⁽³⁾	D

Explanation of Responses:

1. Reflects a 1-for-1.3676 reverse stock split, which will become effective immediately prior to the time the registration statement filed in connection with the issuer's initial public offering becomes effective.

2. This stock option was fully exercisable on the date of grant and, upon exercise, will become subject to a repurchase right in favor of the issuer. The repurchase right lapses as to 25% of the underlying shares on the first anniversary of the grant date and as to the remainder in 36 equal monthly installments beginning one month after the anniversary date of the grant. The repurchase right will terminate upon the completion of the issuer's initial public offering.

3. Reflects a 1-for-1.3676 reverse stock split, which will become effective immediately prior to the time the registration statement filed in connection with the issuer's initial public offering becomes effective, pursuant to which (i) the number of shares of common stock underlying the option was multiplied by 0.7312 and (ii) the exercise price of the option was divided by 0.7312.

4. This stock option was fully exercisable on the date of grant and, upon exercise, will become subject to a repurchase right in favor of the issuer. The repurchase rights lapsed as to 25% of the underlying shares on January 1, 2003 and will lapse as to the remainder in 36 equal monthly installments beginning on February 1, 2003. The repurchase right will terminate upon completion of the issuer's initial public offering of common stock.

5. This stock option vests as to 20% of the underlying shares on September 15, 2006 and as to an additional 1/48th of the remaining underlying shares each month thereafter.

6. These shares will automatically convert into common stock upon the closing of the issuer's initial public offering.

7. N/A

8. Reflects a 1-for-1.3676 reverse stock split, which will become effective immediately prior to the time the registration statement filed in connection with the issuer's initial public offering becomes effective, pursuant to which each one share of Series B Preferred Stock will convert into approximately 0.7312 share of common stock upon the closing of the issuer's initial public offering.

Remarks:

	/s/ Winifred L. Swan Attorney-in-fact for Jeffrey H. Burbank	10/27/2005
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 5 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
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