Investment trust RTW Biotech Opportunities (LON:RTW) scored yet another win as Biomarin Pharmaceutical (NASDAQ:BMRN) snapped up private portfolio company Alesta Therapeutics for $490 million.
Alesta is developing novel oral small-molecule therapies for underserved rare diseases. This transaction represents the sixth portfolio acquisition from RTW Bio’s portfolio in 2026.
Sixth M&A transaction of 2026
Biomarin Pharmaceutical is paying up to $490 million to buy Alesta. The consideration is comprised of $275 million in cash upfront, and a further $215 million upon the achievement of certain milestones.
RTW Bio first invested $2.4 million in the rare disease specialist in 2024 and 2025. As at 31 July 2026, the trust’s stake was valued at $3.8 million and represented 0.4% of NAV. The upfront cash payment represents an estimated 41% uplift in carrying value. Additionally, it boosts RTW Bio’s NAV by $1.6 million or 0.2%.
Pro rata interest retained
Alesta’s lead asset, ALE1, is being developed for the treatment of hypophosphatasia. This is a rare inherited disease that impairs bone and tooth mineralisation. The condition can also cause fractures, tooth loss, muscle weakness, fatigue and pain.
Alesta will spin out all non-ALE1 assets to a newly-formed entity before the deal closes. Existing Alesta shareholders, including RTW Bio, will retain their pro rata interest in this entity.
| AIC Healthcare & Biotechnology Sector | 1-year share price total return (%) | 5-year share price total return (%) |
| Biotech Growth Trust | 103.3 | 45.9 |
| RTW Biotech Opportunities | 83.6 | 34.2 |
| International Biotechnology Trust | 68.4 | 87.4 |
| Polar Capital Global Healthcare | 33 | 63 |
| CT Healthcare Trust | 27.4 | -10.4 |
Source: The AIC/Morningstar
Rod Wong, RTW Bio’s manager, said: ‘We backed Alesta at Series A because of the differentiated profile of ALE1, supported by a management team with a strong track record in rare disease drug development.
‘Biomarin’s decision to acquire the company at pre-Phase 2 data is a clear validation of our strategy of identifying and supporting differentiated science at the earliest stages of the private markets, where the greatest value can be created for our shareholders.’
Wong said the sixth acquisition from RTW Bio’s portfolio this year reflects ‘continued strategic appetite from large-cap pharma facing a cumulative $170 billion patent cliff by 2032.’
In our opinion, RTW Bio is a great way to tap into the biotechnology boom. Due to its dedicated focus on finding ‘transformative’ technologies, the trust is differentiated from most biotech or healthcare funds.
As for the Alesta deal, this looks a win-win for RTW Bio’s shareholders. Firstly, they benefit from a 41% uplift in Alesta’s carrying value. And secondly, they still retain exposure to further milestone payments and to the assets being spun out.
Dealmaking pace to persist?
The Alesta acquisition demonstrates the manager’s ability to identify promising science early. Furthermore, it underlines the appetite of large pharmaceutical companies to replenish their pipelines as patent expiries loom.
Wong expects the current pace of dealmaking to persist. Moreover, he argues RTW Bio ‘remains well positioned across both its public and private portfolios to benefit’.
