CUSIP No. 039697107
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SCHEDULE 13G
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Page 3
of 8 Pages
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1
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NAME OF REPORTING
PERSONS
Rock Springs Capital Master Fund LP
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2
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CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP
(a)
o
(b)
o
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3
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SEC USE ONLY
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4
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CITIZENSHIP OR PLACE OF ORGANIZATION
Cayman Islands
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NUMBER OF
SHARES
BENEFICIALLY
OWNED BY
EACH
REPORTING
PERSON
WITH
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5
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SOLE VOTING POWER
0
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6
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SHARED VOTING POWER
2,390,187
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7
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SOLE DISPOSITIVE POWER
0
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8
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SHARED DISPOSITIVE POWER
2,390,187
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9
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AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
2,390,187
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10
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CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES
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o
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11
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PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)
5.02%
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12
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TYPE OF REPORTING PERSON
PN
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CUSIP No. 039697107
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SCHEDULE 13G
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Page 4
of 8 Pages
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Item 1.
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(a) Name of Issuer
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Ardelyx, Inc.
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(b) Address of Issuer’s Principal
Executive Offices
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34175 Ardenwood Blvd., Suite 200
Fremont, CA 94555
Item 2.
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(a) Name of Person Filing
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Rock Springs Capital Management LP
Rock Springs Capital Master Fund LP
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(b) Address
of Principal Business Office, or, if none, Residence
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Rock
Springs Capital Management LP
650 South Exeter, Suite 1070
Baltimore, MD 21202
Rock
Springs Capital Master Fund LP
c/o Walkers Corporate Limited
Cayman Corporate Centre
27 Hospital Road
George Town, Grand Cayman, KY1-9008, Cayman Islands
Rock
Springs Capital Management LP - Delaware
Rock
Springs Capital Master Fund LP - Cayman Islands
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(d) Title of Class of Securities
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Common
Stock, par value, $0.0001 per share (the “Common Stock”)
039697107
CUSIP No. 039697107
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SCHEDULE 13G
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Page 5
of 8 Pages
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Item 3. If
this statement is filed pursuant to §§240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:
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(a)
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¨
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Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o);
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(b)
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¨
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Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c);
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(c)
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¨
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Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c);
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(d)
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¨
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Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8);
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(e)
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o
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An investment adviser in accordance with §240.13d-1(b)(1)(ii)(E);
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(f)
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¨
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An employee benefit plan or endowment fund in accordance with §240.13d-1(b)(1)(ii)(F);
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(g)
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¨
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A parent holding company or control person in accordance with §240.13d-1(b)(1)(ii)(G);
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(h)
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A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);
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(i)
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A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the
Investment Company Act of 1940 (15 U.S.C. 80a-3);
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(j)
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A non-U.S. institution in accordance with §240.13d-1(b)(1)(ii)(J);
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(k)
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A group, in accordance with §240.13d-1(b)(1)(ii)(K). If filing as a non-U.S. institution in accordance with §240.13d-1(b)(1)(ii)(J),
please specify the type of institution:
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CUSIP
No. 039697107
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SCHEDULE 13G
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Page
6 of 8 Pages
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Item
4. Ownership
Provide
the following information regarding the aggregate number and percentage of the class of securities of the issuer identified
in Item 1.
As of
the date of this filing, the Reporting Persons may be deemed to be the beneficial owners of 2,390,187 shares of Common Stock.
The Reporting Persons hold 2,250,000 shares of Common Stock and 140,187 warrants to purchase the Common Stock. The percent of
class is determined by dividing the number of shares of Common Stock beneficially owned by the Reporting Persons by
47,585,326, the number of shares of Common Stock (47,445,139) issued and outstanding as of August 2, 2017 combined with the
number of warrants (140,187) held by the Reporting Persons.
(a) Amount
beneficially owned:
Rock Springs Capital
Management LP: 2,390,187
Rock Springs Capital Master
Fund LP: 2,390,187
(b) Percent
of class:
Rock Springs Capital
Management LP: 5.02%
Rock Springs Capital Master
Fund LP: 5.02%
(c) Number
of shares as to which the person has:
(i) Sole
power to vote or to direct the vote:
Rock Springs Capital
Management LP: 0
Rock Springs Capital Master
Fund LP: 0
(ii)
Shared power to vote or to direct the vote:
Rock Springs Capital
Management LP: 2,390,187
Rock Springs Capital Master
Fund LP: 2,390,187
(iii)
Sole power to dispose or to direct the disposition of:
Rock Springs Capital
Management LP: 0
Rock Springs Capital Master
Fund LP: 0
(iv)
Shared power to dispose or to direct the disposition of:
Rock Springs Capital
Management LP: 2,390,187
Rock Springs Capital Master
Fund LP: 2,390,187
Item
5. Ownership of Five Percent or Less of a Class
If this statement is being filed to report the fact that as of the date hereof the reporting person has ceased to be the beneficial
owner of more than five percent of the class of securities, check the following