13D Filing: Baker Bros. Advisors and Seattle Genetics Inc (SGEN)

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Page 7 of 12 – SEC Filing

SCHEDULE 13D

CUSIP No.  812578102       Page   7   of   12    Pages
1

NAMES OF REPORTING PERSONS

FBB3 LLC

2 CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (See Instructions)

(a) ¨

(b) ¨

3 SEC USE ONLY
4

SOURCE OF FUNDS (See Instructions)

OO

5

CHECK
BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 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

12,678

8

SHARED VOTING POWER

0

9

SOLE DISPOSITIVE POWER

12,678

10

SHARED DISPOSITIVE POWER

0

11

AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

12,678

12 CHECK
BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES (See Instructions)
¨
13

PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

(1)

14

TYPE OF REPORTING PERSON (See Instructions)

OO

(1) The percentage of ownership is less than 0.1%, based
on 142,716,597 shares of common stock
as of April 26, 2017 as reported in the Issuer’s 10-Q filed with the SEC on
May 1, 2017.

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