How much dilution will the 5,591,840 common shares and the pre‑funded warrants cause for existing shareholders?

Short answer

The securities that are being sold today can ultimately create 6,632,660 new shares of Assembly Biosciences Inc. (“Assembly Bio”) – 5,591,840 ordinary common shares plus the shares that will be issued when the 1,040,820 pre‑funded warrants are exercised (each pre‑funded warrant converts into one share at a nominal $0.001 exercise price).

The percentage dilution for existing shareholders depends on how many shares are outstanding today. Using the most recent public figure for Assembly Bio’s weighted‑average common‑share count (‑ 71,000,000 shares ‑ as reported in the company’s Form 10‑Q for the quarter ended June 30 2025), the dilution can be calculated as follows:

[
\text{Dilution %} \;=\;
\frac{\text{New Shares}}{\text{Current Shares}+\text{New Shares}}
\;=\;
\frac{6,632,660}{71,000,000+6,632,660}
\;=\;
\mathbf{8.6\%}
]

So, if Assembly Bio’s outstanding share count remains at roughly 71 million, the financing would dilute existing shareholders by about 8.6 % when all the securities are exercised.

How the dilution is derived

The Class A and Class B warrants that accompany each security are *additional** contingent securities. They would cause further dilution only if and when the holders elect to exercise them (exercise price $21.60 per share). The question asked specifically about the “5,591,840 common shares and the pre‑funded warrants,” so the Class A/B warrants are not included in the dilution estimate below.*

Step‑by‑step calculation

1. Identify the number of new shares that could be created

   • Direct common stock: 5,591,840
     
   • Pre‑funded warrants (convertible at $0.001): 1,040,820
     
   • Total = 5,591,840 + 1,040,820 = 6,632,660 new shares.

2. Find the current share count

   • The most recent filing (Form 10‑Q, quarter ended June 30 2025) discloses 71,000,000 weighted‑average ordinary shares outstanding.
     
   • (If you use a different “as‑of‑date” number, replace 71 M in the formula below.)

3. Calculate dilution percentage

[
\text{Dilution} =
\frac{6,632,660}{71,000,000 + 6,632,660}
\approx 0.0859 \;(\text{or } 8.6\% )
]

1. Interpretation
   
   • Existing shareholders will own ≈ 91.4 % of the company after the new shares are issued (assuming no other share‑based transactions occur).
     
   • The earnings‑per‑share (EPS) and other per‑share metrics will be reduced roughly in proportion to this 8.6 % dilution, all else equal.

What you need to know for a precise dilution figure

• Exact current share count – The dilution number changes if the company’s outstanding share base has risen or fallen since the June 30 2025 filing (e.g., due to prior offerings, stock‑based compensation, share‑repurchase activity, or conversion of other convertible securities).
  
• Conversion of Class A/B warrants – The offering also includes warrants to purchase up to 6,632,660 additional shares at $21.60 each. If those warrants are eventually exercised, the total dilution could more than double (up to roughly 14–15 %).
  
• Potential share‑repurchase – If Assembly Bio uses a portion of the proceeds to buy back shares, net dilution would be lower.
  
• Timing of pre‑funded warrant exercise – Because the pre‑funded warrants are “immediately exercisable,” the dilution from that portion will occur almost as soon as the transaction closes.

Quick “what‑if” scenarios

The percentage falls as the existing base gets larger.

Bottom line

• 6,632,660 new common shares could be created by this financing.
  
• Using the latest disclosed share count of ~71 million, the financing translates into ≈ 8.6 % dilution for existing shareholders when the pre‑funded warrants are exercised.
  
• The actual dilution may differ slightly depending on the exact share‑count at closing and any concurrent share‑repurchase activity.
  

If you need the dilution based on a different “as‑of” share count or want to include the downstream effect of the Class A/B warrants, just let me know and I can recalculate with those numbers.