Scenario 1: Ruconest is not effective
The stock price at the time of writing is €1.27. If we assume that the trial returns a negative result, the stock price will obviously decrease. In the corona sell-off, the lowest stock price of Pharming Group was €0.78; at that time Ruconest's association with COVID-19 was practically unknown. This indicates a 39% downside, but in my opinion, that was a very pessimistic time in the stock market.
Ruconest is a profitable product and Pharming Group has built a second factory to make even more of it. The worst-case scenario still implies that you buy a profitable company at a p/e ratio of 23 with multiple products in the pipeline. You are not even buying it at the 2020 all-time high.
Also, HAE patients will still require Ruconest treatment, so there is no reason to believe that COVID-19 is negatively impacting Pharming Group's existing business.
Scenario 2: Ruconest is effective
If Ruconest turns out to be an effective COVID-19 treatment, it is obvious that the value created for shareholders and economies could be immense. The current market cap of Pharming Group is €800 million. This was considerably less than the market cap addition that Gilead Sciences saw when it announced Remdesivir might be effective at treating COVID-19.
The upside could easily be 2-fold, 3-fold or even 4-fold if Ruconest is effective. The only investment required is performing clinical trials to determine the effect on COVID-19 cases. Ruconest is an FDA-approved medicine, with facilities to produce it. So the risks involved are quite small.
The high likeliness of Ruconest being an effective treatment makes the risk/reward in my opinion worthwhile to consider.