Silence Therapeutics: Insider Buys Signal Turnaround in Undervalued RNAi Play

Silence Therapeutics (SLN), a biotech firm developing RNA interference (RNAi) therapies for rare diseases and cardiovascular conditions, has long been overshadowed by peers like Alnylam and Arrowhead. But recent developments—including significant insider buying, robust institutional support, and advancing clinical trials—suggest the stock may finally be poised to capture its fair value. For investors seeking a mispriced biotech play with near-term catalysts, SLN presents a compelling risk-reward opportunity.

Richard Griffiths' Insider Buying: A Vote of Confidence

Richard Griffiths, Silence's largest shareholder and founder of Ora Capital, has been aggressively buying shares in 2025. According to SEC filings, he purchased 82,606 American Depositary Shares (ADS) between June 22–24, 2025, at an average price of $5.97 per share, totaling approximately $0.49 million. These purchases, part of a broader $2.7 million stake increase since May, have boosted his total holdings to 24.4% of the company.

Griffiths' activity is significant for two reasons:
1. Alignment with Shareholders: His purchases mirror moves by institutional investors like Artal Group (up 123.4% in holdings) and Lombard Odier Asset Management (up 34.05%), signaling consensus about SLN's undervalued status.
2. Timing: The buys coincide with Silence's upcoming clinical milestones, suggesting Griffiths sees near-term catalysts to unlock value.

Institutional Ownership Dynamics: Stability Amid Shifts

Institutional investors control 98.7% of Silence's shares, with 21 buyers and 9 sellers in the last year. While some funds, like Deep Track Capital, reduced stakes (-48.76%), major holders like Artal Group and Vivo Capital have doubled down. Notably:
- Total institutional inflows reached $144.86 million in the past year, far exceeding outflows of $13.12 million.
- Redmile Group, a top 5 holder, trimmed its stake slightly (-7.68%), but its $34.5 million market value still underscores confidence.

The high concentration of institutional ownership poses a liquidity risk if sentiment turns negative. However, the inflows suggest most investors remain constructive, particularly as the company's cash runway extends to 2027—a critical buffer for executing its clinical strategy.

Clinical Pipeline: Near-Term Catalysts Ahead

Silence's RNAi platform targets high-need areas like rare blood cancers and cardiovascular disease. Two programs stand out:

1. Divesiran (SLN124):
2. Indication: Polycythemia Vera (PV), a rare blood disorder.
3. Milestone: Phase 1/2 SANRECO trial data showed 85% reduction in phlebotomy needs and a favorable safety profile. Phase 2 results (anticipated by mid-2025) could validate sustained efficacy, potentially leading to FDA approval discussions.

4. Regulatory: Already holds Fast Track and Orphan Drug designations.

5. Zerlasiran (SLN360):

6. Indication: Reducing lipoprotein(a) (Lp(a)), a genetic cardiovascular risk factor.
7. Status: Phase 2 data showed 81-85% Lp(a) reduction over 60 weeks, with no serious safety issues. Silence is seeking a partner to share costs for the Phase 3 cardiovascular outcomes trial, which is now “Phase 3 ready” pending a collaboration.

Valuation and Risks

Silence's market cap of $271 million is dwarfed by its peers' multi-billion valuations, despite its promising pipeline. Key risks include:
- Partnership Dependence: Zerlasiran's Phase 3 delay hinges on securing a partner, though ongoing discussions provide hope.
- Dilution: Share count increases could dilute existing investors' stakes.
- Regulatory Hurdles: Late-stage trials must prove clinical benefit, not just biomarker improvements.

Investment Thesis

Silence Therapeutics is a classic “value in biotech” story. Griffiths' insider buying, coupled with institutional support and upcoming catalysts, creates a high-probability scenario for a valuation re-rating. Key triggers include:
- Divesiran Phase 2 data (mid-2025), which could validate its potential as a PV therapy.
- Zerlasiran partnership announcement, which would unlock capital for Phase 3.
- Cash runway extension, reducing near-term financing risks.

For investors with a 12–18 month horizon, SLN offers asymmetric upside: limited downside given its institutional backing and cash position, while catalysts could boost the stock by 50–100% if trials succeed.

Final Take

Silence Therapeutics is a rare case where insider buying, clinical momentum, and institutional conviction align to suggest a turning point. While risks remain, the combination of undervalued stock, near-term data readouts, and a robust RNAi platform positions SLN as a standout play in a crowded biotech space. Investors seeking to capitalize on mispriced assets with clear catalysts should take note.