Sage Therapeutics SAGE announced that its partner Biogen BIIB has made an unsolicited, non-binding proposal offer to acquire the SAGE shares that it does not already own for $7.22 per share. The offer price represents a premium of 30% on Sage Therapeutics’ closing price of $5.55 on Friday.

At present, Biogen owns a 10.2% stake in SAGE, per a SEC filing by the company. Sage Therapeutics’ board will review and evaluate the offer and will come to a final decision.

SAGE’s stock was up 46% in after-hours trading on Friday in response to the news while Biogen was down slightly.

Biogen’s shares have declined 40%, while Sage Therapeutics’  stock has been down 79.1% in the past year, compared with a decrease of 15.9% for the industry.

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BIIB & SAGE’s Partnership for Zurzuvae

Sage Therapeutics and Biogen have a collaboration deal for the commercialization of Zurzuvae, which was approved for treating postpartum depression (PPD) in August 2023.

Biogen and Sage equally share profits and losses for the commercialization of Zurzuvae in the United States. In outside U.S. markets, Biogen records product sales (excluding Japan, Taiwan, and South Korea where Shionogi holds the rights) and pays royalties to Sage Therapeutics. Zurzuvae has not yet been approved in the EU.

Biogen and Sage Therapeutics were also developing Zurzuvae for another indication, major depressive disorder (“MDD”). However, the FDA issued a complete response letter to Biogen for the MDD indication in August 2023, requesting the companies to conduct more clinical studies. In October 2024, the companies announced that they will not pursue further development of Zurzuvae in the MDD indication as more time and investment would be required for conducting additional studies.

If Biogen acquires Sage Therapeutics, it will get full ownership of Zurzuvae. Biogen had earlier said that the launch uptake of Zurzuvae is outperforming expectations.

SAGE’s Several Pipeline Setbacks

Sage Therapeutics has faced several pipeline setbacks in the past couple of years.

In November 2024, Sage Therapeutics decided to stop the development of its neuropsychiatric candidate, dalzanemdor (formerly SAGE-718), for all indications. Mid-stage studies on the candidate for all three indications — cognitive impairment associated with Huntington’s Disease, mild cognitive impairment (MCI) and mild dementia in Alzheimer’s Disease and MCI associated with Parkinson’s disease — failed to meet the primary endpoints.

In September, Biogen terminated its rights under the collaboration and license agreement with Sage for the SAGE-324 (BIIB124) program in essential tremor (ET). A phase II study on SAGE-324 for the chronic treatment of ET failed in July 2024.

BIIB and SAGE’s Zacks Rank & Stocks to Consider

While Sage Therapeutics has a Zacks Rank #2 (Buy), Biogen has a Zacks Rank #3 (Hold).

Some top-ranked stocks from the biotech sector are Puma Biotechnology PBYI and Castle Biosciences CSTL, each sporting a Zacks Rank #1 (Strong Buy) at present. You can see the complete list of today’s Zacks #1 Rank stocks here.

In the past 60 days, estimates for Castle Biosciences’ 2025 bottom line have narrowed from a loss of $1.88 per share to a loss of $1.84 per share. In the past year, shares of CSTL have surged 51.0%.

CSTL’s earnings beat estimates in each of the trailing four quarters, the average surprise being 172.72%.

In the past 60 days, estimates for Puma Biotechnology’s 2025 earnings per share have increased from 52 cents to 55 cents. In the past year, shares of PBYI have declined 33.1%.

PBYI’s earnings beat estimates in three of the trailing four quarters while missing the same on the remaining occasion, the average surprise being 32.78%.

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