Harpoon Therapeutics stock (US4135961044): restructuring after Merck takeover and pipeline focus

Harpoon Therapeutics is reshaping its business after being acquired by Merck & Co. The immuno?oncology specialist is advancing its tri?specific T?cell engager pipeline while winding down its former Nasdaq listing. What matters now for investors following the story from the US and Europe?

Harpoon Therapeutics has entered a new phase after agreeing to be acquired by Merck & Co., shifting the focus for investors from standalone growth to integration and pipeline execution within a large pharma environment, according to a merger announcement published on 01/08/2024 by Merck and Harpoon on the company’s website and via regulatory filings Merck press release as of 01/08/2024 and Harpoon investor update as of 01/08/2024.

As of: 16.05.2026

By the editorial team – specialized in equity coverage.

At a glance

• Name: HARP (Harpoon Therapeutics)
• Sector/industry: Biotechnology, immuno?oncology
• Headquarters/country: South San Francisco, United States
• Core markets: United States and global oncology drug markets via partnerships
• Key revenue drivers: Research collaborations and potential milestone payments from pipeline programs
• Home exchange/listing venue: formerly Nasdaq (ticker: HARP) before completion of the Merck transaction
• Trading currency: US dollar (USD)

Harpoon Therapeutics: core business model

Harpoon Therapeutics focuses on developing novel T?cell engaging biologic therapies designed to redirect a patient’s immune cells to attack cancer, using its proprietary TriTAC and next?generation ProTriTAC platforms to create multi?specific antibodies targeting tumor antigens and T?cell receptors, according to the company’s overview page last updated in 2024 Harpoon company profile as of 2024.

The business model historically relied on funding from equity markets and upfront payments from collaboration partners, with the long?term objective of generating product revenue and milestones as candidates progressed through clinical trials, a strategy described in Harpoon’s 2023 annual report filed with the SEC on 03/28/2024 covering the fiscal year 2023 SEC Form 10?K as of 03/28/2024.

Unlike large commercial biopharma peers, Harpoon did not yet have an approved product on the market and instead concentrated on early? and mid?stage clinical development, making its valuation and strategic options highly sensitive to trial readouts, partnership structures and access to capital, as outlined in the risk factors section of the same 2023 Form 10?K filed on 03/28/2024 SEC risk disclosure as of 03/28/2024.

With the Merck acquisition, Harpoon’s business model is effectively being folded into a much larger R&D and commercialization platform, potentially providing greater financial resources and global reach for its oncology programs while at the same time removing the standalone public equity exposure that Nasdaq investors previously used to access the pipeline, according to the joint transaction closing communication published on 03/12/2024 Merck transaction close update as of 03/12/2024.

Main revenue and product drivers for Harpoon Therapeutics

Before the merger, Harpoon Therapeutics did not generate material product sales and instead reported collaboration revenue and research funding linked to its partnerships, with total revenue of 35.9 million USD for the year ended 12/31/2023 as disclosed in the 2023 annual report filed on 03/28/2024, while net loss remained substantial, reflecting ongoing clinical development and administrative expenses Harpoon 2023 results as of 03/28/2024.

The company’s lead clinical asset HPN328, a DLL3?targeting T?cell engager for small cell lung cancer and other neuroendocrine tumors, represented a key value driver, with updated Phase 1/2 data presented in 2023 suggesting anti?tumor activity and manageable safety in heavily pre?treated patients, according to data summarized for investors in a corporate presentation released on 11/02/2023 Harpoon corporate deck as of 11/02/2023.

Additional pipeline candidates, including HPN217 targeting BCMA in multiple myeloma and other TriTAC or ProTriTAC programs, also contributed to Harpoon’s strategic value by offering exposure to multiple hematologic and solid tumor indications where large markets exist and high unmet medical need remains, a point emphasized in the pipeline overview included with the same 2023 investor presentation dated 11/02/2023 Harpoon pipeline overview as of 11/02/2023.

For Merck, the acquisition provided access to Harpoon’s T?cell engager platforms, which can potentially be combined with the larger company’s existing oncology portfolio and development capabilities to create new treatment options and lifecycle strategies, according to Merck’s deal rationale section in the 01/08/2024 acquisition announcement that highlighted synergy opportunities with its established cancer franchise Merck deal rationale as of 01/08/2024.

Why Harpoon Therapeutics matters for US investors

Although Harpoon Therapeutics is no longer independently listed on Nasdaq following completion of the Merck takeover in March 2024, the story remains relevant for US investors who follow oncology innovation and large?cap pharma pipelines, since Harpoon’s assets may influence Merck’s long?term growth profile and capital allocation, as implied in the transaction closing release dated 03/12/2024 that noted the strategic fit within Merck’s oncology research network Merck oncology focus as of 03/12/2024.

For US?based market participants, the Harpoon acquisition illustrates how innovative but loss?making biotech companies often transition from high?volatility small?cap stocks into components of diversified pharma portfolios, highlighting the importance of M&A activity as an exit pathway and as a driver of value recognition for early shareholders, a trend discussed across sector commentary in 2024 by several investment banks and industry observers who pointed to ongoing consolidation in oncology research Financial Times sector analysis as of 04/05/2024.

For investors in Germany and the broader European market who follow US healthcare equities via ADRs, funds or large?cap pharma holdings, Harpoon’s integration into Merck underscores how niche US research platforms can eventually influence the earnings trajectory and risk profile of globally held blue?chip stocks, thereby linking early?stage biotech innovation in South San Francisco to portfolios far beyond the United States, as reflected in global investor materials accompanying the Merck deal press kit published on 01/08/2024 Merck global investor materials as of 01/08/2024.

Conclusion

Harpoon Therapeutics has moved from a high?risk, clinical?stage biotech stock into a research platform embedded within Merck, following a transaction announced on 01/08/2024 and closed on 03/12/2024, which valued the company primarily for its T?cell engager technology and oncology pipeline. The stand?alone equity narrative around funding, trial milestones and Nasdaq trading dynamics has given way to questions about how efficiently Merck can integrate and advance the acquired programs within its broader portfolio. For investors in the US and in Germany who track healthcare exposure through diversified pharma holdings or sector funds, Harpoon’s trajectory offers a concrete example of how early?stage innovation, capital market volatility and strategic M&A intersect in modern immuno?oncology, while also underlining that clinical, regulatory and integration risks remain key factors to monitor through Merck’s future disclosures.

Disclaimer: This article does not constitute investment advice. Stocks are volatile financial instruments.