GSK PLC (GSK) SHARES: 2025 PERFORMANCE IN UK, KEY DRIVERS, MILESTONES AND RISKS —'26 OUTLOOK

How did GSK shares perform in the UK in 2025?

GSK plc (LSE: GSK), one of the United Kingdom’s leading pharmaceutical giants, experienced a complex investment landscape throughout 2025. The company’s share price journey over the year was shaped by a combination of operational performance, macroeconomic pressures, and healthcare sector dynamics.

GSK opened 2025 trading near the 1,400 GBX level, continuing at a moderate valuation post its consumer healthcare spin-off (Haleon) in previous years. By Q4 2025, GSK shares were up approximately 9% year-to-date. While the share price never experienced substantial breakout highs, its steady progression reflected investor confidence in its core pharmaceuticals and vaccines business.

Several key factors underpinned this performance:

• Vaccine leadership: GSK’s prevention portfolio, particularly within RSV (respiratory syncytial virus) and shingles vaccines, outperformed expectations. Strong early adoption of its Arexvy vaccine in the UK and other international markets added significant revenue uplift.
• Pipeline momentum: Clinical trials for multiple oncology and HIV treatments progressed into late-stage development. Notably, Phase III results for daprodustat, a treatment for anaemia due to chronic kidney disease, were favourable, fuelling investor sentiment.
• Revenue stability: The company posted resilient quarterly revenues, with consistent year-on-year growth. Adjusted earnings per share rose modestly, supported by operating efficiency improvements and geographical revenue diversification.
• Macroeconomic resilience: GSK’s relatively defensive sector positioning insulated it from broader market volatilities, particularly during periods where UK inflationary pressure and rate uncertainty affected cyclical stocks.

Additionally, investor optimism was bolstered by updates from the UK government on healthcare funding and NHS strategic partnerships, which signalled a favourable domestic environment for pharma corporations.

However, the share price was not without challenges. Mid-year saw a temporary dip following missed expectations in Q2 respiratory medicine sales and investor concerns surrounding litigation risk linked to legacy Zantac claims. GSK reaffirmed its legal cost provisions, which aided in the eventual recovery of investor trust.

On balance, GSK’s share trajectory in 2025 can be viewed as solid, with mid-single-digit returns reflective of the firm’s maturing innovation engine and decreased exposure to its previously embattled consumer division. For income-oriented investors, the company maintained its progressive dividend policy, yielding roughly 3.7% annually — aligning it well within blue-chip expectations in the current FTSE 100 landscape.

What drove GSK’s performance and strategic progress?

GSK’s commercial success in 2025 was underpinned by a focus on innovation, vaccine expansion, and robust R&D execution. With a refined corporate focus, post-Haleon spin-off, GSK sharpened its strategy around infectious diseases, oncology, and immunology.

1. Pharmaceutical pipeline productivity

GSK highlighted several key late-stage programmes that drove investor enthusiasm. Among them:

• Otilimab: Initially developed for rheumatoid arthritis, its reassessment for COVID-related inflammatory indications yielded new licensing considerations during healthcare consortium discussions.
• Belantamab mafodotin: A drug for multiple myeloma which, following regulatory delays, was finally cleared for targeted patient groups via conditional EMA approval.
• Daprodustat: Achieved significant Phase III milestones, setting up strong potential for broader market approvals in 2026, including NHS usage.

2. Vaccine portfolio expansion

Key revenue contributors were:

• Shingrix: One of the most successful non-COVID vaccines globally, maintained growth in the UK due to demographic ageing and increased awareness campaigns supported by NHS guidance.
• Arexvy: RSV vaccine uptake surprised on the upside, with UK paediatric and elderly demographics showing higher inoculation willingness than forecasted.

3. Strategic alliances and M&A

GSK executed notable bolt-on acquisitions in 2025 to support its pipeline. The £1.2bn acquisition of Aiolos Bio, a respiratory therapeutic start-up, underscored GSK’s willingness to externally supplement its internal R&D programmes.

In addition, continued partnerships with Vir Biotechnology and Alector helped progress antiviral and neuroinflammatory treatments, respectively. These alliances not only fed potential growth avenues but also enhanced R&D cost efficiency through shared platforms.

4. Operational and financial management

GSK improved its operating margin in 2025, aided by:

• Deduplication of post-Haleon administrative structures
• Manufacturing scale-up of key treatments in Scotland and Belgium
• Foreign exchange neutralisation through currency hedging in volatile markets

Its full-year adjusted EPS reached projected guidance, reflecting tight cost control and product mix enhancements generating higher gross margins.

5. ESG performance and stakeholder trust

GSK also made progress towards its 2030 environmental goals, winning praise for its decarbonisation of UK logistics operations and water neutrality projects at major laboratories in Hertfordshire.

These actions improved stakeholder perception, reinforcing its position as a long-term defensive asset within UK equity portfolios.

What risks and opportunities face GSK in 2026?

As GSK heads into 2026, investors are likely focusing on balancing the firm’s strengthening innovation capacity against known and emerging headwinds. Although 2025 ended on a relatively stable note, several themes remain highly relevant when assessing the company’s investment case for the next year.

1. Regulatory and litigation overhangs

While GSK settled several claims related to Zantac in 2025, certain US class action lawsuits remain unresolved. Any adverse rulings in 2026 may impact cashflows and investor sentiment. Additionally, regulatory scrutiny is anticipated to remain high, particularly concerning accelerated vaccine approvals and safety disclosures post-COVID pandemic learnings.

Eyes will also be on whether the Medicines and Healthcare products Regulatory Agency (MHRA) approves GSK's pending novel HIV regimens, which are pivotal to the group's long-term virology strategy.

2. Competitor pressure and emerging market dynamics

Market share erosion in key therapeutic areas is likely a concern, with Pfizer, Moderna and AstraZeneca all intensifying focus on immunology and rare diseases. GSK must defend its positions through ongoing data efficacy, patent strength, and access strategies via public health systems.

In emerging markets, currency devaluations and geopolitical instability in Latin America and sub-Saharan regions could impact repatriation of profits and demand forecasting.

3. Innovation outcomes and pipeline risks

While its R&D momentum is encouraging, GSK faces binary outcomes from several clinical readouts expected in late 2026. Investors should watch:

• Progress of asthma bio-therapeutics in UK-based trials
• HPV treatment efficacy extensions in adolescents
• Neurological drug developments under the Alector collaboration

Setbacks in any of these domains could disrupt revenue expectations and rerate how markets view GSK’s innovation premium.

4. Dividend reliability and capital discipline

GSK’s dividend remains a primary draw for FTSE income investors. While coverage remains intact (above 1.5x), future increases hinge on sustaining FCF growth amid investment needs. Capital allocation priorities in 2026 are likely to weigh R&D expansion versus shareholder returns carefully.

Further share buybacks — limited in 2025 — may return if cash generation strengthens, particularly if the firm divests additional non-core assets or exceeds vaccine sales forecasts.

5. Strategic clarity and leadership stability

CEO Emma Walmsley enters 2026 facing intensified scrutiny around strategic focus and growth delivery. While her leadership has recovered credibility post-Haleon, any missteps in communicating long-term objectives, especially around oncology, may refuel investor concerns on future value unlocks.

Still, many analysts consider GSK a firmly placed FTSE 100 constituent, with reasonable valuation upside stemming from its consolidation around fewer, more impactful therapeutic areas.

Ultimately, those investing or tracking GSK into 2026 should closely monitor future R&D news flow, litigation settlements, and NHS policy interaction — all of which may shape whether the company continues its steady ascent or faces renewed volatility.