Carlyle and SK Capital Partners have announced an extension of the tender offer to acquire all outstanding common stock of bluebird bio, Inc. The new expiration date is set for one minute after 11:59 p.m., New York City time, on May 28, 2025. Previously, the offer was scheduled to expire on May 12, 2025.

Equiniti Trust Company, LLC, the depositary for the offer, informed Merger Sub that as of May 12, approximately 2,502,927 shares of bluebird common stock had been validly tendered and not withdrawn. Shareholders who have already tendered their shares do not need to take any further action due to this extension.

The offer is being conducted under terms outlined in the Offer to Purchase dated March 7, 2025. This includes conditions described in "Section 15—Conditions to the Offer," such as a majority tender of outstanding shares and other customary closing conditions.

Founded in 2010, bluebird bio has made significant strides in gene therapy with FDA approvals for three therapies within two years. The company focuses on severe genetic diseases and holds a substantial data set in ex-vivo gene therapy.

Carlyle operates as a global investment firm managing $441 billion in assets across various segments. Meanwhile, SK Capital focuses on life sciences and specialty materials sectors with a portfolio generating around $12 billion annually.

This communication does not constitute an offer or solicitation regarding securities of bluebird. Investors are advised to review related documents filed with the SEC before making decisions about tendering their shares.

For more information or inquiries:

- Bluebird Investors: Courtney O’Leary at coleary@bluebirdbio.com

- Bluebird Media: Jess Rowlands at jess.rowlands@bluebirdbio.com

- Carlyle Media: Brittany Berliner at brittany.berliner@carlyle.com

- SK Capital: Ben Dillon at bdillon@skcapitalpartners.com