Module 06 · Venture Finance

SAFEs, convertible notes, and pre-priced instruments

Module 05 covered priced equity rounds — Series A and beyond, where the investor buys preferred stock at a specific valuation. But most pre-seed and seed-stage capital today doesn't move that way. It moves through SAFEs and convertible notes — instruments specifically designed to defer the valuation decision to a later priced round, when the company has enough information for the price to be honest. This module covers how these instruments work, why they exist, and the surprising ways they affect a founder's eventual ownership.

35 minute read
8 sections
5 international cases
1 worked SAFE conversion
6-question quiz
Section 01

Why not just price the equity?

The previous module described a Series A as if the valuation step were straightforward: investors and founders negotiate a number, that number becomes the post-money valuation, the investor buys preferred stock at the implied per-share price. That works at Series A because the company has enough traction — revenue, customers, growth metrics, team — to ground the valuation in something. At pre-seed and seed, the company has none of that. The "valuation" is essentially fictional.

Consider a founder raising $500K for a two-person company with a prototype and three pilot customers. What's the company worth? A buyer of common-stock equity would need to fix a number. $3M? $8M? $15M? Any of these is defensible. None has a rigorous basis. The "valuation" is whatever the founder and investor agree on, with the founder pushing up and the investor pushing down, anchored only by what comparable deals have priced at recently.

For decades, this awkwardness was handled by simply doing it anyway — early rounds were priced equity rounds with semi-fictional valuations. The problem: priced rounds require legal documents (term sheet, definitive documents, amended certificate of incorporation, stockholders agreement). Negotiating those documents for a $500K round was almost as expensive in legal fees as negotiating them for a $5M round. The friction made small early rounds disproportionately costly.

The fundamental trade

Pre-priced instruments defer the valuation decision to a later moment when it can be made honestly. Investors give the company money today; the instrument converts to equity at a future qualified financing round, at whatever valuation that round produces (with some adjustments). The investor doesn't have to negotiate a valuation now. The company doesn't have to issue priced equity yet. Both sides save legal fees and the awkwardness of pricing what cannot be priced.

Two main instruments dominate this space: the convertible note (the original, dating from the 1990s) and the SAFE (Simple Agreement for Future Equity, invented by Y Combinator in 2013). They serve the same purpose but have very different mechanics. The next two sections cover each.

Section 02

The convertible note — the original instrument

A convertible note is, technically, debt. The investor lends money to the company. The company is legally obligated to pay it back at some maturity date — unless a qualifying event happens first, in which case the debt converts to equity. The dual nature is the whole point: it's debt that almost always becomes equity.

Instrument · Convertible note

Debt that converts to equity at a future priced round

Principal · Interest rate (typically 6-8%) · Maturity (typically 18-24 months) · Valuation cap and/or discount rate

The note's principal is the investor's check. Interest accrues at a stated rate (typically 6-8%). At maturity, if no qualifying event has occurred, the principal plus accrued interest becomes repayable as a debt — though in practice this almost never happens; the parties usually agree to extend the maturity. The qualifying event is a "qualified financing," typically defined as a priced equity round above some threshold ($1M or $3M or $5M, depending on the note's drafting). When the qualified financing happens, the principal plus accrued interest converts into the same series of preferred stock the new investors are buying.

The key economic terms in a convertible note are the valuation cap and the discount rate, both designed to reward the note investor for taking earlier (riskier) money risk:

  • Valuation cap. A maximum valuation at which the note will convert. If the future priced round happens at a $30M post-money valuation but the note has a $10M cap, the note converts as if the round had priced at $10M — meaning the note investor gets 3× the equity they would have gotten without the cap.
  • Discount rate. A percentage discount on the conversion price. A 20% discount means the note converts at 80% of the priced-round price. If the round prices at $5 per share, the note converts at $4 per share — meaning the note investor gets 25% more shares than someone paying the round's price.
  • The better of the two. When a note has both a cap and a discount, it converts at whichever produces more shares for the note investor — the cap-implied price or the discount-adjusted price, whichever is lower.

Why notes were dominant for so long

From the late 1990s through about 2013, convertible notes were the default instrument for early-stage rounds in the U.S. The note format had real advantages: it was legally well-understood (debt is older than venture capital itself), tax-efficient in some structures, and standardized enough that legal fees were manageable. Convertible notes still dominate in some sectors (life sciences, hardware) and many international markets.

The downsides of notes are mostly secondary, but they accumulated over time and motivated YC's invention of the SAFE. Notes accrue interest (which seems small but compounds across years of bridge rounds). They have maturity dates (which create awkward conversations if the priced round is delayed). Bankruptcy treatment of a note holder differs from an equity holder (notes are senior). And in some jurisdictions, the debt classification has consequences for the company's tax accounting.

🇺🇸 Anchor case · Convertible notes in the pre-SAFE era
Many of the most prominent U.S. startups of the 2005-2012 period raised their seed rounds on convertible notes — Stripe, Dropbox, Pinterest, Square, Airbnb, and others all used the structure for at least part of their early financing. The Stripe note rounds in particular became reference templates for the industry: clean structure, founder-friendly terms (low discount rates, generous caps), and rapid conversion at the first qualified financing. The pattern across these companies — note today, convert at Series A — became the standard rhythm of U.S. early-stage financing in that era.
Section 03

The SAFE — Y Combinator's 2013 invention

In late 2013, Y Combinator's lawyers and partners introduced a new instrument: the SAFE (Simple Agreement for Future Equity). The pitch was right there in the name. Notes were getting longer and more complex, and most of the complexity served no real purpose for the typical seed-stage transaction. The SAFE stripped the structure down to what actually mattered: the right to convert into future preferred stock, with a cap or discount or both, and almost nothing else.

Instrument · SAFE

A right to future equity, without the debt overhead

No interest · No maturity · Just: investor cash today, conversion at next priced round, with a cap and/or discount

A SAFE is not debt. It does not accrue interest. It has no maturity date. It is, structurally, just a contractual right to receive equity at a future qualified financing event. The investor gives the company money today; in exchange, the company promises to issue them shares at the next priced round, calculated using the SAFE's cap and discount.

The simplification matters in a few specific ways. No interest accruing means a SAFE held for three years doesn't quietly grow into more shares the way a note does. No maturity means there's no awkward "the note matured but we haven't raised yet" conversation that often happens in real seed-stage timelines. Not debt means the company doesn't have to carry a debt obligation on its books and doesn't face the legal complications of unpaid debt at bankruptcy. The SAFE just sits there as an outstanding promise to issue equity, getting resolved only when the priced round happens.

Convertible note

  • Technically debt
  • Accrues interest (6-8% typically)
  • Has a maturity date (18-24 months)
  • Cap and/or discount
  • ~3-8 pages of legal text
  • More common internationally
  • Required in some jurisdictions

SAFE

  • Not debt — contractual right to future equity
  • No interest
  • No maturity
  • Cap and/or discount
  • ~5 pages of legal text
  • U.S. seed-stage default since ~2018
  • Spreading internationally

For U.S. seed-stage financings, the SAFE became the de facto standard between 2015 and 2018 and remains so today. Convertible notes still exist in U.S. early-stage practice but are increasingly the exception rather than the rule. The pattern is reversed in many international markets where notes remain dominant — partly for legal reasons in jurisdictions where SAFEs don't fit the local law cleanly, and partly because the SAFE template is U.S.-centric and hasn't been adapted everywhere.

🇺🇸 Anchor case · Y Combinator and the SAFE template
Y Combinator's seed accelerator deal — the standard $500K investment for ~7% of the company — has been documented in SAFE form since 2014. The YC SAFE template, published openly on Y Combinator's website, has become an industry-standard reference document. Tens of thousands of seed-stage rounds globally have used either the YC SAFE template directly or close adaptations of it. The 2018 redesign (which we cover in the next section) reshaped the document; the structure remains the most-used early-stage venture instrument in the U.S.
Section 04

Pre-money vs post-money SAFEs — YC's 2018 redesign

The original 2013 SAFE was a "pre-money" SAFE. In 2018, Y Combinator redesigned it as a "post-money" SAFE. The change was mechanically subtle but materially affected which party — founder or investor — absorbs the dilution from other SAFEs raised before the priced round. The shift is one of the most commonly misunderstood pieces of mechanics in early-stage venture, and it matters to founders raising on SAFEs today.

The pre-money SAFE (2013-2018)

In the original pre-money SAFE, the cap referred to the pre-money valuation at conversion — the company's value before the qualifying round's new money came in. If a founder raised three SAFEs at a $10M cap, then raised a Series A at a $20M post-money valuation, the SAFEs would convert as if the company had $10M pre-money. The math required figuring out how many new shares to issue to all the SAFE holders, all at once, and the result was that the founders' dilution from later SAFEs was uncertain — they couldn't know how diluted they'd end up until all the SAFE conversions were computed at the priced round.

The opacity made it easy for founders to under-estimate their eventual dilution. A founder doing what seemed like small SAFE rounds at $10M caps could end up much more diluted than they expected once everything converted, particularly if the priced round happened at a much higher valuation.

The post-money SAFE (2018-present)

The 2018 redesign changed the cap to refer to the post-money valuation at conversion of the SAFE itself. In a post-money SAFE with a $10M cap, the investor gets exactly $X invested ÷ $10M of the company — for example, a $500K SAFE at a $10M post-money cap gives the investor exactly 5.0% of the company at conversion (subject to the discount comparison).

The change makes the founder's eventual dilution from each SAFE fixed and knowable at the time of signing. A founder who signs three SAFEs each at a $10M post-money cap, $500K each, knows they will be diluted by exactly 15% from those SAFEs alone (3 × 5.0%). If they then add a $3M Series A at a $20M post-money, that's another ~15% dilution on top. The math becomes additive and predictable.

⚠️ The hidden cost of post-money SAFEs
Making the math knowable to founders also made it more favorable to investors. Under the pre-money SAFE, the dilution from later SAFEs partially fell on the earlier SAFE investors (their share of the post-money got diluted by the new SAFEs converting alongside them). Under the post-money SAFE, the dilution from later SAFEs falls entirely on the founders — each SAFE investor's percentage is locked in by their post-money cap, so the founders absorb everything else. For most founders, the post-money SAFE is a worse deal economically than the pre-money SAFE would have been at the same cap. The trade-off is predictability for the founder vs. cost — and many founders accept the trade without realizing they're making it.

Why YC moved to post-money

Y Combinator's stated rationale was simplicity: founders couldn't predict their dilution under the pre-money SAFE, and that uncertainty was producing bad decisions. The post-money SAFE made the math transparent, which YC argued was worth the dilution cost. The argument has merit — predictability genuinely matters, and many founders raising on pre-money SAFEs really did end up much more diluted than they expected. But founders raising on post-money SAFEs today should understand the structural cost they're paying for that predictability. If they raise three SAFEs at $10M post-money caps, the total dilution will be 15% from SAFEs alone, regardless of what else happens before the priced round.

This is a place where the experienced founder's intuition departs from the inexperienced founder's. An experienced founder negotiating SAFEs in 2026 will push for higher caps not just because they want better valuations but because each $1M raised at a $10M post-money cap costs them exactly 10% of the company — and that math is unforgiving.

Section 05

Caps and discounts — how the economics work

Both SAFEs and convertible notes use two main economic mechanisms to reward the early investor for taking earlier (riskier) money: the valuation cap and the discount rate. Understanding how these interact at conversion is essential to understanding what's actually being agreed to.

The valuation cap

The cap is the maximum valuation at which the instrument will convert. The mechanic is simplest in the post-money SAFE: a $500K SAFE at a $10M post-money cap converts to exactly 5.0% of the company at the qualified financing, regardless of what valuation the qualified financing actually prices at. If the priced round happens at a $20M post-money valuation, the SAFE investor still gets their 5.0% — meaning they're effectively buying at a $10M post-money price while everyone else in the round buys at $20M. The earlier investor's reward for getting in earlier (and at higher risk) is the locked-in price.

From the founder's perspective: the cap is the most-important single term in any SAFE or note. A $500K check at a $5M cap costs the founder 10% of the company; the same $500K at a $20M cap costs only 2.5%. Founders should negotiate caps hard.

The discount rate

The discount rate gives the SAFE or note investor a percentage discount on the price of the qualified financing. A 20% discount means the investor's conversion price is 80% of the priced round's price. If the priced round is at $5 per share, the SAFE/note converts at $4 per share — meaning the early investor gets 25% more shares than a new investor paying full price.

The discount is a smaller benefit than a tight cap in most realistic scenarios — a 20% discount on a Series A might give the early investor a 25% boost, while a tight cap can give them 2-3× the equity they'd otherwise get. Some instruments have both, in which case the investor converts at whichever produces more shares (typically the cap-implied price).

The combined-mechanism rule

When a SAFE or note has both a cap and a discount, the conversion happens at whichever produces more shares for the early investor — the cap-implied price or the discount-adjusted price, whichever is lower. Most well-drafted instruments include both, with the cap usually being the binding constraint when the priced round happens at high valuation.

Conversion price = min(Cap-implied price, Discount-adjusted price)

"Most Favored Nation" and other secondary terms

Some SAFEs include a "Most Favored Nation" clause — if a future SAFE is issued with better terms (higher cap, larger discount), the existing SAFE's terms get adjusted to match. The clause matters when a founder is raising over an extended period and may issue SAFEs at progressively higher caps as the company makes progress. Without MFN, early SAFE investors who took the riskiest money on the worst terms watch later investors get progressively better terms; with MFN, they at least match. Founders should expect early sophisticated SAFE investors to ask for MFN.

Section 06

KISS and international variants

The SAFE and convertible note are U.S.-centric instruments. International venture markets have evolved their own approaches, some converging on U.S. patterns and some staying distinctively local.

KISS (Keep It Simple Security)

500 Global (formerly 500 Startups) introduced KISS in 2014 as an alternative to the SAFE. KISS comes in two versions — "KISS Debt" (which is structurally a convertible note) and "KISS Equity" (which is structurally similar to a SAFE). The KISS templates added a few investor-friendly features that the SAFE deliberately omitted, including MFN provisions and clearer protective rights. KISS is used by 500 Global's portfolio and some other accelerators but never caught on at the scale of the SAFE.

The European convertible loan note

In the UK and across continental Europe, the convertible loan note (CLN) — also called the convertible loan agreement — remains the dominant pre-priced instrument. Structurally it resembles a U.S. convertible note: it's debt, accrues interest, has a maturity date, converts at a qualified financing with a cap and/or discount. UK CLNs are usually drafted under English law with the British Venture Capital Association template as a starting point. SAFEs are spreading in Europe but slowly; in many European jurisdictions, the SAFE structure creates legal or tax complications that don't exist in U.S. law, and the CLN remains the easier path.

India — Compulsorily Convertible Debentures

Indian venture uses a distinctive instrument called the Compulsorily Convertible Debenture (CCD). Structurally it's a debt instrument that must convert to equity at maturity (the "compulsorily" part). The compulsory-conversion structure is required by Indian regulatory frameworks that limit foreign debt holdings but allow foreign equity. For Indian seed-stage rounds, CCDs serve roughly the same function as U.S. convertible notes, with the additional regulatory layer baked in.

China — varied and shifting

Chinese venture historically used a mix of instruments, with the choice often driven by whether the financing was structured for an eventual U.S. IPO (in which case U.S.-style instruments were adapted) or for a Chinese domestic path. The post-2021 regulatory environment has reshaped this — VIE structures targeting U.S. IPOs are less common, and Chinese-domestic structures use a parallel set of instruments tied to Chinese corporate law. The instruments themselves are less well-documented in English than U.S. SAFEs are.

🇬🇧 Anchor case · UK CLN conventions
Most UK seed-stage rounds in the 2020-2025 period have used Convertible Loan Notes drafted on the basis of the British Private Equity and Venture Capital Association (BVCA) template. The CLN typically includes a cap, a discount (often 20%), interest accruing at 5-8%, and a maturity of 24 months. Index Ventures, LocalGlobe, Hoxton Ventures, and most UK-based seed funds use CLN structures by default. SAFEs have been increasingly used in UK rounds led by U.S. investors but remain the exception rather than the rule. The pattern reflects both legal tradition and the UK venture ecosystem's slightly more conservative norms compared to U.S. early-stage practice.
Section 07

The SAFE stack problem

One of the most consequential developments in early-stage venture over the last decade has been the rise of the "SAFE stack" — companies raising multiple SAFEs across multiple rounds at different caps before any priced round occurs. The SAFE stack creates a hidden complexity that catches many founders off guard at the priced round.

The pattern

A modern company might raise its capital like this: $500K at a $5M cap from friends and family (Round 1, pre-seed). Six months later, $1.5M at a $10M cap from a seed fund (Round 2). Six months later, $2.5M at a $20M cap from a larger seed fund (Round 3). At each step, the founder is making decisions that seem reasonable in isolation — raising what's needed to reach the next milestone, at a cap that reflects the company's progress. The founder is not setting a "valuation"; they're just stacking SAFEs.

Then the Series A comes. The priced round prices at $50M post-money. All three SAFE rounds convert at once. The conversion math:

Round Amount Cap Conversion % of co.
Round 1 (pre-seed)$500K$5M10.0%
Round 2 (seed)$1.5M$10M15.0%
Round 3 (seed extension)$2.5M$20M12.5%
SAFE total$4.5M37.5%

The SAFE holders, in aggregate, get 37.5% of the company. The Series A investors then take their 20% on top of that. The option pool typically takes another 12%. The founders, after all of this, end up owning around 30% of the company — much less than they probably expected when they were doing the individual rounds.

⚠️ The compounding dilution surprise
Each SAFE round looks reasonable in isolation. A $500K check at a $5M cap is 10% — not crazy for pre-seed. A $1.5M check at a $10M cap is 15% — slightly aggressive but in range. A $2.5M check at a $20M cap is 12.5% — generous given the company's progress. The founder never agreed to a single 37.5% transaction; they agreed to three transactions that compound to 37.5%. This is the SAFE stack problem, and it is the modern equivalent of the option pool shuffle from Module 05 — a hidden dilution mechanism that catches founders off guard.

The implication: founders raising on SAFEs should model the compound dilution carefully, ideally with a simple spreadsheet showing what their ownership will be after all expected SAFEs have converted, plus the eventual Series A. Modeling this in advance lets the founder see the trajectory before they're committed. Module 09 (Cap Table Math) will return to this with full mechanical detail.

Section 08

A worked example — SAFE conversion at Pipework's Series A

To make the mechanics concrete, modify the Pipework example from Module 02. In this version, Pipework's seed money came not from a priced seed round but from two SAFEs. The Series A then prices, and both SAFEs convert. We'll track the cap-table evolution through the conversion.

Setup

Asha and Marco each take 5,000,000 shares at founding — 10,000,000 total, 100% of the company. Total fully-diluted shares: 10,000,000.

Six months later, they raise a SAFE from Friends & Family Capital for $500,000 at a $5M post-money cap. Twelve months after that, they raise a second SAFE from Seed Fund A for $1,500,000 at a $10M post-money cap. They now have $2M in cash and two outstanding SAFEs. No shares have actually been issued for the SAFEs yet — they're outstanding promises to issue equity at the qualified financing.

The Series A prices

Twelve months later, Pipework has built the product, hit $2M in ARR, and raises a $15M Series A at a $60M pre-money / $75M post-money valuation. At this moment, the SAFEs convert. The conversion math:

  • SAFE 1 ($500K at $5M post-money cap): converts to exactly 500,000 / 5,000,000 = 10.0% of the post-money company.
  • SAFE 2 ($1.5M at $10M post-money cap): converts to exactly 1,500,000 / 10,000,000 = 15.0% of the post-money company.
  • Series A ($15M at $75M post-money): converts to exactly 15,000,000 / 75,000,000 = 20.0% of the post-money company.
  • Option pool: a 12% post-money option pool is reserved as part of the Series A.

The SAFE investors get their fixed percentages because of the post-money SAFE structure — the percentages are locked at the cap, independent of the Series A price. The result is the founder dilution that compounds across all three rounds plus the option pool. Walk through the cap table:

Pre-financing cap table (just before Series A pricing, SAFEs outstanding)

HolderShares (notional)Pre-conversion %
Asha (co-founder)5,000,00050.0%
Marco (co-founder)5,000,00050.0%
SAFE 1 ($500K at $5M cap)— (outstanding)
SAFE 2 ($1.5M at $10M cap)— (outstanding)
Total issued10,000,000100.0%

Post-Series-A cap table (SAFEs converted, option pool established, Series A invested)

Holder% of post-money companyValue at $75M
Asha (co-founder)21.5%$16.1M
Marco (co-founder)21.5%$16.1M
Option pool12.0%$9.0M
SAFE 1 (Friends & Family)10.0%$7.5M
SAFE 2 (Seed Fund A)15.0%$11.3M
Series A investor20.0%$15.0M
Total100.0%$75.0M

What the math shows

The founders, who started at 50% each, end up at 21.5% each after the SAFE conversions, option pool, and Series A. Their combined ownership has dropped from 100% to 43%. They've been diluted by 57 percentage points across two SAFE rounds and one priced round.

Compare this to the priced-equity version from Module 02, where the same founders ended up at 25% each after a $10M post-money priced seed round and the same $75M Series A. The SAFE-stack version produced 3.5 percentage points more dilution per founder — meaning the founders ended up owning meaningfully less of the company by routing the seed money through SAFEs at the caps they negotiated, compared to a priced seed at $10M post-money. The difference is not negligible: at a $1B IPO, 3.5% per founder is $35M each.

This is the cumulative effect of the SAFE stack with mismatched caps. The Friends & Family SAFE at a $5M cap was a particularly expensive piece of paper — the founders effectively gave up 10% of the company for $500K, when a priced seed round at $10M would have given up half that. Sometimes early money on aggressive terms is the only money available; founders should at least know what they're trading.

The pragmatic takeaway

SAFEs and notes are excellent instruments for the moment when a valuation cannot honestly be set. They are not free, and the cumulative dilution from a stack of SAFEs can substantially exceed what an equivalent priced seed would have cost. Founders should: (1) negotiate caps aggressively, since every dollar of cap matters mechanically; (2) model the compound dilution across all expected SAFEs plus the eventual Series A before signing the first one; (3) consider whether a priced seed at a fair cap is the better path even when SAFEs are easier in the moment.

Next module

Module 07 · Cap Table Math

The numerical core of the track. How to actually build and read a cap table. The full mechanics of pre-money to post-money math, the option pool shuffle in detail, preference-stack waterfalls at exit, and the dilution calculations that determine who owns what when the company sells.

Self-examination

Test your understanding

Six questions on pre-priced instruments — what they are, how they convert, the difference between pre- and post-money SAFEs, and the dilution dynamics of the SAFE stack.

Module 06 · Self-examination