MRK, NEUP Stocks Drop As Merck Scraps Another Alzheimer’s Drug Trial Under Neuphoria Partnership

• The trial tested whether adding MK-1167, a daily capsule, to standard Alzheimer’s medicines could improve memory and thinking.
• Merck ended the trial after an early planned review of the results showed the drug did not perform well enough to continue.
• Merck, however, is still active in Alzheimer’s research.

Shares of Merck & Co. Inc. (MRK) fell over 2% on Wednesday after the company terminated a mid-stage study of its Alzheimer’s drug MK-1167 being developed with Neuphoria Therapeutics (NEUP), citing business reasons.

The company is no longer looking for participants for the trial intended to evaluate the efficacy and safety of MK-1167 as adjunctive therapy in participants with mild to moderate Alzheimer's disease dementia, according to a post to ClinicalTrials.gov.

NEUP stock closed the regular trading session down 19% and fell another 3% after hours. 

What Happened With The Trial?

The trial tested whether adding MK-1167, a daily capsule, to standard Alzheimer’s medicines could improve memory and thinking.

Patients were randomly assigned to receive one of three doses of MK-1167 or a placebo. Neither the patients nor the researchers knew who got the real drug. The main goals were to check for improvements on a common test of thinking skills after 24 weeks and to monitor safety.

The study began enrolling people in December 2024 and aimed for about 350 participants across multiple countries. It is now closed, with the last patients finishing in early June 2026.

Why Did Merck Stop It?

Merck ended the trial after an early planned review of the results showed the drug did not perform well enough to continue. The company has stated that no safety concerns were identified during the trial.

MK-1167 was designed to help brain cells communicate better by boosting specific signals linked to memory and attention.

Merck previously also discontinued the development of another drug being developed with Neuphoria called MK-4334. The drug completed one early-stage study in 2022 that tested its effects on brain signals in healthy volunteers and people with schizophrenia. However, a planned second early-stage study in patients with Alzheimer’s disease who were already taking the drug donepezil was withdrawn before any participants were enrolled. No other compounds from the particular Merck–Neuphoria partnership have entered clinical trials. 

Merck, however, is still active in Alzheimer’s research. It continues to test another experimental drug, MK-2214, that targets a different protein in the brain. Results from that study are expected in 2029.

How Did MRK Retail Traders React?

On Stocktwits, retail sentiment around MRK stock fell from ‘bullish’ to ‘neutral’ territory over the past 24 hours, while message volume remained at ‘high’ levels.

A Stocktwits user voiced optimism for MRK stock hitting all-time highs by month-end.

According to data from Koyfn, 19 of the 29 analysts covering MRK rate it ‘Buy’ or ‘Strong Buy’ while nine rate it ‘Hold’ and one rates it ‘Strong Sell.’The 12-month average price target on the stock is $130.78, representing a potential upside of over 4% from the stock’s last close.

MRK stock has gained 19% year-to-date. 

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