Carlyle and SK Capital close in on Bluebird Bio acquisition

USA—Private equity firms Carlyle and SK Capital have announced they expect to complete their acquisition of gene therapy company Bluebird Bio on June 9, 2025.

The deal follows an amended buyout agreement that increased their per-share offer from US$3.00 to US$5.00, securing enough investor support to proceed with the transaction.

When Carlyle and SK’s original offer expired, 59.8% of bluebird’s common stock had been tendered, a significant increase from 25.6% two weeks earlier under the initial terms.

The buyers required at least 50% plus one share to close the deal.

Initially, the firms offered US$3.00 per share plus a contingent value right (CVR) worth US$6.84 per share, payable only if bluebird’s sales of its three gene therapies reached US$600 million in any 12-month period by the end of 2027.

Bluebird’s gene therapies include Lyfgenia for sickle cell disease, Zynteglo for transfusion-dependent beta-thalassemia, and Skysona for cerebral adrenoleukodystrophy.

These treatments generated US$84 million in sales in 2024 and US$39 million in the first quarter of 2025, which is far below the milestone needed to trigger the CVR payout.

The original offer valued bluebird at roughly US$29 million upfront, while the revised deal is worth about US$45 million upfront.

Investors could still opt for the original $3-per-share plus CVR structure if preferred.

Founded 15 years ago, bluebird bio will become a private company following the acquisition. The company had been under financial pressure, facing potential default on loans from Hercules Capital and the risk of bankruptcy.

This buyout comes after bluebird’s valuation plummeted from over US$10 billion, reflecting challenges in commercializing its gene therapies and broader difficulties in the gene therapy industry.

Bluebird struggled particularly in Europe, where it failed to agree on pricing for Zynteglo with regulators and exited the market in 2021.

CEO Andy Obenshain described the European market as “broken” and “untenable” for a small innovative company at that time.

In the U.S., bluebird had anticipated rapid sales growth for Zynteglo and Skysona, both FDA-approved in 2022 and priced at US$2.8 million and US$3 million respectively.

However, the expected boost from Lyfgenia’s FDA approval in December 2023 was dampened by competition from Vertex’s CRISPR gene editing therapy Casgevy, which was priced lower at US$2.2 million compared to Lyfgenia’s US$3.1 million.

The acquisition by Carlyle and SK Capital, both experienced investment firms, provides bluebird with the capital and management support needed to scale its commercial operations and continue developing gene therapies.

Carlyle manages US$441 billion in assets globally, while SK Capital focuses on transformative investments in science and materials sectors with around US$9 billion under management.

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