13D Filing: Baker Bros. Advisors and Idera Pharmaceuticals Inc. (IDRA)

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Page 3 of 10 – SEC Filing

CUSIP No.   45168K306   Page   3   of   10   Pages
1.

NAMES OF REPORTING PERSONS

Baker Bros. Advisors (GP) LLC

2.

CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*

(a)
¨

(b)
¨

3.

SEC USE ONLY

4.

SOURCE OF FUNDS*

OO

5.

CHECK
BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEM 2(d) or 2(e)

¨

6.

CITIZENSHIP OR PLACE OF ORGANIZATION

Delaware

NUMBER
OF SHARES
BENEFICIALLY
OWNED
BY EACH
REPORTING
PERSON WITH
7.

SOLE VOTING POWER:

38,956,461 (1)

8.

SHARED VOTING POWER:

0

9.

SOLE DISPOSITIVE POWER:

38,956,461 (1)

10.

SHARED DISPOSITIVE POWER:

0

11.

AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON:

38,956,461 (1)

12.

CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES*

¨

13.

PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

18.0% (1)(2)

14.

TYPE OF REPORTING PERSON*

HC, OO

(1) Includes 157,500 shares of the common stock of the Issuer
underlying options directly held by Julian C. Baker, a principal of the Adviser, 157,500 shares of the common stock of the Issuer
underlying options directly held by Dr. Kelvin M. Neu, an employee of the Adviser and 20,316,327 shares of common stock issuable
upon the exercise of the 2018 Warrants (as defined below).
(2) Based on 195,635,196 shares of the Issuer’s common
stock outstanding as of January 3, 2018 as reported in the Issuer’s in the Issuer’s 8-K Exhibit 2.1 filed with the
SEC on January 22, 2018.

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