13G Filing: Viking Global and aTyr Pharma Inc (LIFE)

Schedule 13G PAGE 9 of 14

CUSIP No. 002120103

ITEM 1(a). NAME OF ISSUER:
aTyr Pharma, Inc.

ITEM 1(b). ADDRESS OF ISSUER’S PRINCIPAL EXECUTIVE OFFICES:
3545 John Hopkins Court, Suite #250
San Diego, California 92121

ITEM 2(a). NAME OF PERSON FILING:
Viking Global Investors LP (“VGI”),
Viking Global Opportunities GP LLC (“Opportunities GP”),
Viking Global Opportunities Portfolio GP LLC
(“Opportunities Portfolio GP”),
Viking Global Opportunities Illiquid Investments Sub-Master LP
(“Opportunities Fund”),
O. Andreas Halvorsen, David C. Ott and
Rose S. Shabet (collectively, the “Reporting Persons”)

ITEM 2(b). ADDRESS OF PRINCIPAL OFFICE OR, IF NONE, RESIDENCE:
The business address of each of the Reporting Persons is
55 Railroad Avenue, Greenwich, Connecticut 06830.

ITEM 2(c). CITIZENSHIP:
VGI is a Delaware limited partnership; Opportunities GP and
Opportunities Portfolio GP are Delaware limited
liability companies; and Opportunities Fund is a Cayman Islands
exempted limited partnership.
O. Andreas Halvorsen is a citizen of Norway.
David C. Ott and Rose S. Shabet are citizens of
the United States.

ITEM 2(d). TITLE OF CLASS OF SECURITIES:
Common stock, par value $0.001 per share (“Common Stock”)

ITEM 2(e). CUSIP NUMBER: 002120103

ITEM 3. IF THIS STATEMENT IS FILED PURSUANT TO 13d-1(b) OR 13d-2(b) OR (c),
CHECK WHETHER THE PERSON FILING IS A:

(a) [ ] Broker or dealer registered under Section 15 of the
Act

(b) [ ] Bank as defined in Section 3(a)(6) of the Act

(c) [ ] Insurance Company as defined in Section 3(a)(19) of
the Act

(d) [ ] Investment Company registered under Section 8 of the
Investment Company Act of 1940

(e) [ ] Investment Adviser registered under Section 203 of the
Investment Advisers Act of 1940: see Rule 13d-
1(b)(1)(ii)(E)

(f) [ ] Employee Benefit Plan, Pension Fund which is subject
to the provisions of the Employee Retirement Income
Security Act of 1974 or Endowment Fund; see Rule 13d-
1(b)(1)(ii)(F)