SEC Form 4 · accession 0001012975-15-000092

bluebird bio, Inc. · BLUE

Statement of changes in beneficial ownership, as filed. Original on EDGAR ↗

Table I — non-derivative securities

Table II — derivative securities

Explanation of responses

• F1Distribution of Common Stock held by a limited partnership to its partners for no consideration.
• F2These shares are owned directly by ARCH Venture Fund VII, L.P. ("ARCH Fund VII"). The sole general partner of ARCH Fund VII is ARCH Venture Partners VII, L.P. ("ARCH Partners VII"). The sole general partner of ARCH Partners VII is ARCH Venture Partners VII, LLC ("ARCH VII LLC"). The Managing Directors of ARCH VII LLC, Robert T. Nelsen, Keith Crandell and Clinton Bybee, are deemed to have voting and dispositive power over the shares and may be deemed to beneficially own Fund shares held by ARCH Fund VII. Each Managing Director disclaims beneficial ownership of these securities, except to the extent of his pecuniary interest therein, and this report shall not be deemed an admission that such Managing Director is the beneficial owner of such securities for Section 16 or any other purpose.
• F3Change from indirect to direct ownership of shares previously reported as beneficially owned by the reporting person. Steven Gillis owns an interest in ARCH Partners VII but does not have voting or investment control over the shares held by ARCH Fund VII and disclaims beneficial ownership of such shares, except to the extent of any pecuniary interest therein, and this report shall not be deemed an admission that Steven Gillis is the beneficial owner of such securities for Section 16 or any other purpose.