Calculating the dilution of multiple Bons de Souscription d'Actions Accord d'Investissement Rapide (BSA Air) instruments with different valuation caps requires modeling each tranche as a distinct conversion event against your fully diluted share base. Because a BSA Air defers valuation until a future qualified equity round, each ticket converts at the lower of its individual valuation cap or the negotiated round discount. When founders accept capital across rolling closes with escalating caps, each tranche converts at a different share price, issuing varying share volumes that dilute existing equity holders and complicate institutional rounds.
Understanding this mathematical interaction before signing agreements is critical for early-stage startup operations and cap table management. Stacking convertibles without continuous simulation often leads to unexpected equity loss for founding teams at their Series Seed.
How Does a Founder Manage Runway Early?
Managing early runway requires balancing quick capital intake against long-term equity cost. When founders focus exclusively on extending survival by a few months, they often treat pre-seed funding as isolated injections rather than an interconnected liability on their capitalization table (cap table).
Sound runway management connects everyday bookkeeping and compliance with forward-looking capital strategy. Instead of signing separate convertibles whenever cash runs low, founders should establish clear financing milestones based on projected operating expenses and realistic hiring timelines. Calculating your burn rate and maintaining rigorous finance ops prevents emergency fundraising, where founders are forced to grant aggressive discounts or low valuation caps.
A coherent capital strategy structures funding options around business progress rather than convenience. Early financial planning must map how each tranche of convertible capital will translate into equity ownership when an institutional investor eventually prices the company.
To place this decision in context, back-office automation for bootstrapped B2B founders before the first ops hire brings together complementary guidance on the same field.
The Mechanics of BSA Air Conversion at a Priced Round
The BSA Air operates similarly to an American Simple Agreement for Future Equity (SAFE), granting an investor the right to receive common or preferred shares during a future qualifying round. The conversion price per share is determined by selecting whichever formula produces the lower share price for the investor.
The investor receives shares based on two reference metrics:
- The discounted price, which multiplies the share price of the qualifying round by one minus the agreed discount rate.
- The valuation cap price, which divides the contract valuation cap by the total number of existing shares at conversion.
The investor receives the lower of those two prices as a financial reward for taking early risk. As outlined in the Swanbase analysis of BSA Air dilution, the typical discount sits between 10% and 25%, and the SeedLegals contract analysis it reports places two thirds of signed agreements between 10% and 20% discount. Valuation caps range from 1 to 3 million euros for initial French seed rounds and 5 to 8 million euros for bridge rounds depending on traction, again per the SeedLegals figures reported by Swanbase. The floor, mandatory under French law per the article, is frequently calibrated so the cap equals 2 times the floor in the majority of observed SeedLegals contracts.
When the qualified round valuation exceeds the cap, the cap determines the share price. Conversely, if the startup raises at a pre-money valuation lower than the cap, the discount rate applies.
For a single instrument, how to calculate BSA-AIR dilution with cap and floor details the base mechanics; this article covers stacking several caps.
What Cap Table Mistakes Hurt Founders Later?
The most common cap table mistakes to avoid involve staggered bridge notes with variable caps signed during fragmented pre-seed rounds.
According to research highlighted in the Swanbase analysis of BSA Air dilution, fragmented pre-seed rounds stretching over several months trap founders upon fully diluted conversion. When market traction improves, founders frequently raise valuation caps for subsequent angel checks. For instance, an entrepreneur might secure an initial investor at a 5 million euro cap, a second after signing a major client at a 7 million euro cap, and a third at an 8 million euro cap.
The mechanical friction becomes apparent during a priced round. As detailed in the Swanbase analysis, if a company issues a first BSA Air ticket of 80,000 € at a 5 million euro cap and a second ticket of 120,000 € at a 7 million euro cap before closing a priced round at a 10 million euro pre-money valuation, the first instrument converts at 5 € per share while the second converts at 7 € per share.
This creates multiple share purchase prices for the same underlying stock class, which incoming venture capital funds often resist. Institutional investors entering a Series Seed typically demand a clean cap table. Faced with asynchronous convertible notes, venture funds may require founders to renegotiate, harmonize terms, or absorb the legal cost of modeling intricate conversion mechanisms prior to closing. Legal counsel generally recommends grouping angel investors into a single subscription window with identical economic terms to preserve cap table clarity.
This approach also connects with what a credible B2B pitch deck looks like for a 2026 seed, which clarifies the next choice.
Step-by-Step Simulation: Multi-Stage BSA Air Dilution
To understand how multiple BSA Air agreements dilute equity, consider the sequential fundraising progression documented in the Swanbase analysis of BSA Air dilution.
Initial Position and Angel Tranches
A solo founder establishes a company with an initial equity pool of 1,000,000 shares, representing 100% ownership.
The founder then raises a first angel commitment of 50,000 € through a BSA Air with an 18 month longstop date, a 5 million euro cap, and a 20% discount rate. Soon after, three additional angels invest 150,000 € on identical terms, bringing total pending BSA Air investments to 200,000 € at a 5 million euro valuation cap. At this stage, no new shares are issued, so the legal cap table still shows the founder at 100%, masking future dilution until the priced round takes place.
Conversion at the Seed Round
Twelve months later, an institutional investor leads a priced Seed round, injecting 1,500,000 € at an 8 million euro pre-money valuation, creating a 9.5 million euro post-money valuation.
Before calculating the new lead investor's share allocation, the company converts the outstanding BSA Air instruments:
- Cap share price: 5,000,000 € divided by 1,000,000 shares yields 5 € per share.
- Discounted share price: 8,000,000 € divided by 1,000,000 shares multiplied by 0.80 yields 6.40 € per share.
Because 5 € is lower than 6.40 €, the valuation cap applies, resulting in 40,000 new shares issued to the angel pool for their 200,000 € investment.
Next, the venture fund prices its entry on a fully diluted basis that incorporates the converted notes. Dividing the 8,000,000 € pre-money valuation by the 1,040,000 post-conversion shares produces a share price of 7.69 € for the venture fund, which yields 195,122 shares for their 1,500,000 € investment.
Post-Conversion Capitalization Table
| Shareholder | Share count | Ownership percentage |
|---|---|---|
| Founder | 1000000 | 80.96% |
| Angel pool | 40000 | 3.24% |
| Seed VC | 195122 | 15.80% |
| Total | 1235122 | 100% |
As shown in the Swanbase analysis, the founder moves from 100% to 80.96% equity ownership, absorbing roughly 3.2 percentage points of additional dilution compared to an alternative scenario without convertible notes where the founder would retain 84.2%. In a pedagogical solo scenario raising 200,000 € under an 8 million euro cap and 20% discount followed by a 10 million euro round, the cap and the discount produce the same 8 € share price and the angel receives 25,000 shares, representing 2.44% post-conversion equity before the venture capital check.
When tranches carry distinct caps, this math must be repeated line by line for each instrument, which compounds mathematical complexity and founder dilution.
In practice, how to prepare for your first investor meeting completes this framework with another angle on the same topic.
Structuring Clean Finance Operations Before Series Seed
Managing cap table liabilities requires disciplined back-office execution long before an institutional term sheet arrives. Spreadsheets are often sufficient for basic cap table math, but they lack dynamic integration with broader operational realities such as hiring projections, cash runway, and compliance milestones.
A robust funding roadmap should connect underlying business assumptions directly with capital requirements. Ember supports founders through its Fund Your Growth capability, which replaces a generic list of financing options with a funding path coherent with the project. By reading project documents and connecting relevant evidence to funding decisions, it highlights visible, editable assumptions rather than generating detached financial projections.
Ember structures funding scenarios tailored to the project stage, geography, and operating constraints, linking business modules in a living graph where weak points surface first. This visibility allows early-stage teams to identify dilution risks before signing convertible agreements. Once financing terms are defined, the platform opens a connected Data Room without generating redundant paperwork, organizing financial models, historical traction, and investor materials into structured folders so due diligence proceeds efficiently.
Before deciding, how to build an investor target list for a 2026 raise helps connect this method with adjacent priorities.
Sources
FAQ
Do two BSA Air signed at different caps convert at the same price?
No: each tranche converts at the lower of its own cap divided by the share count and the discounted round price. The Swanbase example shows one tranche converting at 5 €/share and a second at 7 €/share for the same share class, which VCs read poorly.
What caps and discounts does the market actually show on a BSA Air?
Per Swanbase and the SeedLegals contracts it analyzes: typical discount 10-25% (two thirds of deals between 10 and 20%), caps of 1-3M€ in French seed rounds, 5-8M€ in bridges, and a cap often equal to 2 times the mandatory floor.
Why does the cap table still show 100% founder before the round?
Because no shares are issued at signing: BSA Air only convert at the qualified round. That is what hides the dilution; in the example, the founder drops from 100% to 80.96% in a single closing.
How do you avoid different per-share prices across angels?
Group subscriptions in a single window on identical terms, as counsel cited in the analysis recommends, or harmonize before the round. Otherwise each tranche converts at its own price and the incoming VC may demand renegotiation.
Is a spreadsheet enough to track several BSA Air?
For arithmetic yes, but it does not connect the cap table to runway, hiring and milestones. A system linking project documents to funding decisions prevents discovering the stack at term-sheet time.