S-1 Filings Explained: How to Research IPOs Before They Go Public
Learn how to read S-1 registration statements to evaluate IPOs before they start trading. A complete guide to IPO research using SEC filings.
Right before a company goes public, the information gap flips.
For years, only insiders and private investors had detailed numbers. Then, one day, the company drops a monster PDF on the SEC's website that tells you almost everything: how the business works, how fast it's growing, what it's afraid of, who owns it, and how much they want public markets to pay.
That document is the S-1 registration statement.
I've read dozens of these. Some made me excited about companies I had never heard of. Others made me pass on IPOs everyone seemed to love. The S-1 is the closest thing you'll get to opening the hood before the car rolls onto the lot. Media coverage, banker decks, and hot-take threads are just commentary. The S-1 is the source.
This guide is how I actually use S-1s: how to find them, what order to read them in, what to pull out, and which patterns should set off alarms before IPO FOMO kicks in.
What an S-1 Actually Is
Form S-1 is the SEC's standard registration statement for companies that want to sell securities to the public, usually for the first time.
In plain terms: before a company can do an IPO on the NYSE or Nasdaq, it has to convince the SEC, "Here's who we are, here's what we do, here's our financial history, here's what could go wrong, and here's how this offering will work."
A few core points:
- It's filed before the IPO, often weeks or months in advance.
- It covers business description, financials, risk factors, management, ownership, and offering mechanics in one place.
- It's iterative: you see an initial S-1, then a series of S-1/A amendments as the company responds to SEC comments and updates numbers.
- The same filing eventually morphs into the prospectus investors receive when the deal prices.
You can find S-1s on SEC EDGAR or through a more usable front end like Earnings Feed's filings view, which lets you filter by form type.
The S-1 Timeline
Understanding the sequence helps me know where I am in the process when an S-1 pops up.
Initial S-1 This is the "we're going public" moment. The company lays out historical financials, a full risk section, and a description of the business. The price range tends to be missing or just placeholder language. Timing is fuzzy; the company and its bankers are still feeling out demand and dealing with SEC questions.
S-1/A Amendments Over the following weeks, you'll see amended versions (S-1/A). These may update recent quarterly numbers, tweak risk factor wording, add details the SEC asked for, and eventually include an actual proposed price range and share counts. Each amendment is a little closer to launch.
Final Amendment with Price Range When the S-1 shows a real range (e.g., "we expect the price to be between $24 and $28 per share") and more detailed offering terms, the IPO window is close, often within a week or two. At this point, the roadshow is typically underway.
Effectiveness and Pricing The SEC declares the registration "effective." That's the formal green light. The company and bankers then agree on an exact price, file the final prospectus, and trading usually begins the next day.
If I'm watching Earnings Feed, the moment I see an S-1 or S-1/A for a name I care about, I know exactly where the company is on that arc.
How I Read an S-1
Most S-1s are 150-300 pages. If you try to read them front-to-back like a novel, you'll hate your life. I speak from experience.
A better approach is to read in layers, starting broad and only drilling down if the company passes initial smell tests.
Layer 1: Prospectus Summary
The opening "Prospectus Summary" is my orientation. It usually covers:
- What the company does in one or two pages
- A sketch of the market opportunity
- High-level financials (revenue, net income/loss, maybe key metrics)
- Basic offering details (shares offered, use of proceeds in bullet form)
In 10-15 minutes I should be able to answer:
- Do I understand, at a basic level, what this business does?
- Is it roughly profitable, roughly break-even, or deeply loss-making?
- Is growth obviously accelerating, obviously slowing, or not highlighted at all?
If the answer to "do I understand this?" is no, that's already a decision: either dig in more because I'm curious, or accept that this might not be my game.
Layer 2: Risk Factors
Next stop: the Risk Factors section. It's long. It's also where S-1s are weirdly honest.
Companies are legally required to spell out material risks. Their lawyers would rather over-disclose than under-disclose, so you get:
- Customer concentration spelled out as "Customer A accounted for 32% of revenue."
- Regulatory dependencies in unusually direct language.
- Admissions that "we may never achieve profitability" or "we expect to raise additional capital in the future."
Yes, there's boilerplate. You can skim "we operate in a competitive market" and "our stock price may be volatile." What I'm hunting for are risks that are:
- Specific to this company (not generic), and
- Potentially existential (not minor annoyances).
I've also found that how a risk factor is written tells me something. A vague, hand-wavy description of a very real business threat is not inspiring. One that is clear and detailed at least tells me they're not in denial.
Layer 3: Business Section
Once I've decided the company is at least interesting and not obviously a trap, I go to the "Business" section.
This is the detailed look at:
- Products and services
- How they make money (pricing, contracts, subscription vs. transaction, etc.)
- Customer types and go-to-market strategy
- The competitive environment they think they're in
- Their stated growth strategy and "moat"
Here I'm trying to construct a mental model: what is the engine of this business?
For a SaaS company, it might be recurring seat-based revenue plus upsells. For a marketplace, it might be take-rates and transaction volume. For a biotech, it's the pipeline and eventual economics of a successful drug.
If I can't explain that engine in a few sentences after reading this section, I probably don't understand it well enough to guess how it will behave as a public stock.
Layer 4: MD&A
The Management's Discussion and Analysis (MD&A) section is where I see how the people running the company interpret their own data.
They'll walk through:
- Revenue trends and the underlying drivers
- Major expense categories and why they're growing (or shrinking)
- Segment or cohort performance, if relevant
- Non-GAAP metrics they consider important (ARPU, net dollar retention, LTV/CAC, etc.)
Two questions I hold in my head while reading:
- Does management have a sensible, consistent narrative for what the numbers are doing?
- Are they upfront about trade-offs (for example, spending more on growth now at the expense of near-term profitability)?
If the MD&A feels like it's straining to avoid obvious issues, that's worth noting.
Layer 5: Financial Statements
Finally, the actual numbers: income statement, balance sheet, cash flow statement, and associated notes.
This is where I sanity-check the story:
- Is revenue growth as impressive (or not) as they keep saying?
- Are gross margins improving, stable, or deteriorating?
- How much are they spending on sales & marketing, R&D, and G&A as a percentage of revenue, and how is that changing?
- Are operating losses shrinking as a % of revenue, or widening?
- How much cash is on the balance sheet, and what's the cash burn rate? How many quarters of runway do they have?
I don't build a wonky model for every IPO. A rough feel for trajectory, like "growing 40% with improving gross margins and shrinking losses" vs. "growth slowing as losses expand," goes a long way.
Sections I Never Skip
There are a few sections that don't fit neatly into the "read in order" flow, but I consider them too important to miss.
Use of Proceeds
There's a dedicated section where the company explains how it plans to use IPO money.
I'm hoping to see:
- Investment in growth (sales, product, expansion)
- Reasonable debt pay-down
- General corporate purposes in a proportion that feels sane
Red flags include:
- Most of the proceeds earmarked to repay ugly, expensive debt that probably should have been refinanced earlier.
- Large chunks going to pre-IPO investors or insiders cashing out. That's not automatically bad, but if insiders are exiting aggressively on day one, I want to know why I'm supposed to be excited to get in.
Ownership and Lock-Ups
The Principal Stockholders section shows who owns what before the IPO: founders, executives, VC funds, and other large investors.
A few things I look at:
- Will founders and management still own large stakes after the offering?
- Are any of them selling in the IPO itself? If so, how much of their position?
- How concentrated is ownership in one or two funds?
I also pay attention to lock-up periods (when insiders are restricted from selling). These dates matter; they can create additional supply months after the IPO when restrictions expire.
Capital Structure and Voting Rights
Many modern IPOs use dual-class structures (for example, Class A with one vote, Class B with ten votes).
I ask myself:
- After the IPO, who actually controls the company?
- Am I buying real influence, or just economic exposure with almost no say?
I might be fine with founder control. I just don't want to discover it for the first time after something controversial happens.
Related-Party Transactions
Buried in the back is a section on related-party transactions: deals between the company and insiders or their affiliates.
This is where you see:
- The company leasing headquarters from an entity owned by the CEO.
- Loans to or from executives.
- Significant purchases or sales involving companies tied to board members.
These can be benign, especially in younger companies, but patterns of heavy self-dealing are a red flag.
Red Flags That Make Me Slow Down
Not every IPO with issues is uninvestable. But some patterns in S-1s deserve extra caution.
On the financial side:
- Growth decelerating sharply right before the IPO, with no convincing explanation.
- Gross margins trending down in a business that claims scalable unit economics.
- Operating losses widening faster than revenue grows, with no credible path to profitability.
- Heavy dependence on one or two customers for a large chunk of revenue, especially if that's getting worse.
- A balance sheet that looks fragile even before the IPO proceeds hit.
On the structural side:
- A large portion of proceeds going to pay down ugly debt or fund liquidity for insiders rather than the actual business.
- A capital structure that locks in control for a small group indefinitely, with very limited rights for public shareholders.
- A risk factor section that hints at unresolved regulatory questions or investigations in key markets.
None of these are automatic passes. But they should move me from "this sounds cool" to "I'm going to assume the rosy scenario is a bonus, not a base case."
Comparing S-1s
S-1s become even more useful when I look at them side by side.
If three payments companies or four SaaS security vendors file to go public in the same year, I can line up their disclosures and ask:
- Who's actually growing fastest?
- Who has the best gross margins and the clearest path to margin expansion?
- Who has the most concentrated customer base?
- Who burns the most cash for each dollar of new revenue?
The sector stories ("the TAM is huge," "the shift to X is inevitable") start to look generic once everyone uses the same language. The numbers and specific disclosures are where I see separation.
Where to Find S-1s
You can get S-1s directly from SEC EDGAR. Search by form type ("S-1") and ticker or company name.
If you'd rather not relive 1990s web design, you can also:
- Use Earnings Feed to filter the live SEC feed for S-1 and S-1/A filings as they hit EDGAR.
- Click through to a company's profile and see its S-1 alongside later 10-Ks, 10-Qs, 8-Ks, and insider trades once it's public.
Once the company is trading, its investor relations site will usually host the final prospectus under "SEC Filings" or "IPO".
My IPO Research Workflow
I don't turn every IPO into a multi-day research project. A simple tiered workflow helps:
Quick Screen (30 minutes) Read the prospectus summary and skim financial highlights. Decide whether this is even in my circle of competence and whether growth/profitability is interesting enough to warrant more time.
Risk and Business Pass (60-90 minutes) Read the risk factors carefully. Then read the business section with a notebook open and try to write my own one-paragraph description of the model. If I can't, that's telling.
Financial and Structure Close Look (1-2 hours) Go through MD&A and financials, focusing on growth, margins, and cash. Check use of proceeds, ownership, related parties, and voting structure. Make a short list of "pros," "cons," and "unknowables."
Valuation Context (around an hour) Look at the proposed price range and implied market cap. Compare basic multiples (EV/revenue, maybe forward if guidance exists) to similar public companies, adjusted for growth and margin differences.
Decision At the end of this, I'm choosing between "buy at or after IPO if pricing is sane," "watch but only touch after trading settles," or "pass unless the valuation becomes absurdly cheap." The point is making that call based on what the company disclosed, not how loud the hype machine is.
Common IPO Mistakes
A few patterns I try to guard against:
- Headline-only research – Articles emphasize narrative ("disrupting X," "huge market") and early investors. They rarely dwell on risk factors or unit economics.
- Assuming growth extrapolates forever – S-1s often cover the best three-year run a company has had. Growth almost always slows as the base gets bigger.
- Ignoring dilution and overhang – Stock-based compensation, reserved option pools, and future fundraising will all eat into your slice of the pie. Lock-up expirations can dump supply into the market months after the IPO.
- Treating "it popped on day one" as validation – Day-one trading often reflects allocation dynamics and hype, not long-term fair value. Missing the first candle rarely matters if you're playing a multi-year game.
Summary
The S-1 is one of the few moments in a company's life where you, as a public-market investor, may actually know almost as much as the private investors who came before you. It's dense; it's legalistic; it's also your best shot at understanding what you're being asked to buy before the ticker exists.
If you're serious about IPOs, treat the S-1 as required reading. Everything else (interviews, presentations, hot takes) sits downstream from it.
If you want to make that easier to track:
- Create a free Earnings Feed account and add "S-1" to the kinds of filings you care about in your watchlist.
- Use the live filings feed to see new IPO registration statements as soon as they hit EDGAR, not when they show up in a headline.
The SEC has already forced companies to show you their cards. Your job is to actually look at them before you bet.