Startup Equity vs RSUs: The Math They Don't Show You at Signing

You get two offers on the same day. Big tech: $200K base, $300K in RSUs over four years, quarterly vesting. Series B startup: $170K base, 0.3% of the company, and a founder who texts you personally at 9pm. The startup equity vs RSUs math is rarely done honestly, because the parts that matter most never come up in the offer call. Here is the framework.

RSUs Are Simple. Options Are Surprisingly Not.

A Restricted Stock Unit is a promise. The company agrees to give you real shares if you stay long enough. When they vest, you own them outright. No money out of pocket, no strike price to worry about. The value of your RSU is exactly what the stock is worth on vest day. You do not need to understand anything. Shares appear in your brokerage account. Some people build entire careers this way.

Startup equity works differently. Most startup employees receive stock options, not shares. An option is the right to buy shares at a fixed price (the strike price) set on grant day. That price comes from a 409A valuation, an independent appraisal of what common stock is worth.

You own nothing until you exercise. Exercising means writing the company a check: strike price times number of shares. Fifty thousand options at $0.10 is $5,000 to exercise all of them. That sounds manageable. Add taxes and it gets more interesting. Add AMT and it gets genuinely alarming.

Your Grant Percentage Is Already Wrong

When a startup says "0.3% of the company," they mean 0.3% of the current cap table. Every future funding round dilutes that number, and startups that reach acquisition usually raise a lot of rounds.

A typical venture-backed company raises several rounds before a liquidity event. Seed rounds dilute existing holders by 15 to 25%. Series A adds another 20 to 30%. Series B cuts another 15 to 25%. By the time a company IPOs or gets acquired, the original 0.3% grant is closer to 0.12% to 0.17%.

That is still worth something if the company is worth $5 billion. It is worth almost nothing if the company sells for $80 million, which is far more common.

About 90% of startup exits happen quietly through acquisitions, and the median acquisition price for venture-backed companies is around $100 million. That sounds like real money until you understand what happens to the proceeds.

The Liquidation Stack Eats First (and Last)

Investors hold preferred stock. You hold common stock. These are different things, and the difference matters most when a check finally arrives.

When a company is acquired or liquidates, preferred shareholders collect first via a mechanism called a liquidation preference. A standard 1x liquidation preference means investors get their full investment back before common shareholders see a dollar. Many term sheets also include "participating preferred" clauses, which let investors collect their preference and then share pro rata in whatever is left. They get paid first. Then they get paid again.

The result is that a company can sell for a number that looks impressive on a TechCrunch headline and still leave employees with nothing.

Good Technology is the canonical example. BlackBerry acquired the company in 2015 for $425 million. Investors had poured in roughly $300 million with standard preferences. The liquidation stack consumed the majority of proceeds. Most common shareholders, including the engineers who built the product, received little or nothing. The press release said $425 million. The engineers' brokerage accounts said otherwise.

How a $160M acquisition leaves employees with almost nothing

Before accepting any startup offer, ask the company for the total liquidation preference. That number is the floor the exit price must clear before a dollar flows to your common shares. If investors have put in $150 million and the company sells for $160 million, you are dividing $10 million across all common shareholders. That 0.3% stake is worth $30,000 before taxes. Not the $480,000 the raw math suggests.

The 90-Day Trap Nobody Mentions

When you leave a startup, your vested but unexercised options do not belong to you indefinitely. Most startup option agreements give you 90 days to exercise your vested shares or forfeit them entirely. Three months to decide whether to pay your strike price plus taxes, or lose years of vested equity.

The IRS mandates this window for Incentive Stock Options. After 90 days, ISOs convert to NSOs with worse tax treatment, and most companies let unexercised options lapse rather than convert.

The practical consequence: imagine three years at a startup, 75% vested, then a layoff. You have 90 days to come up with cash and commit it to an illiquid company you just left involuntarily. If the 409A price is $2 per share and your strike is $0.20, exercising 30,000 options costs $6,000 plus taxes on $54,000 in paper gains. For ISOs, that $54,000 spread counts as income for Alternative Minimum Tax purposes, even though you cannot sell the shares. The company just showed you the door. Enjoy your tax bill.

Some companies now offer 5- or 10-year exercise windows. Worth asking about before you sign.

You Can Owe Six Figures on Shares That Go to Zero

The AMT problem deserves its own section because engineers have genuinely gone bankrupt over it. This is not hyperbole.

When you exercise ISOs and hold the shares rather than immediately selling, the spread between your strike price and the fair market value at exercise counts as AMT income, but not regular income. Exercise a large batch when the 409A is high and you may owe six figures in AMT on gains you cannot access because the shares are private and illiquid.

If the company subsequently fails or the share price drops, you can apply for an AMT credit in future years. But you still paid the tax in real cash, on shares that are now worthless. This happened to a significant number of engineers during the dot-com collapse and the 2022 private market correction. They paid taxes on millions. Then the company went under. The AMT credit clawed some of it back over years. Not all of it.

The fix is to exercise options early, when the spread is small, paired with an 83(b) election. This only works within 30 days of your grant. Most engineers do not know to ask about it at the offer stage. The startup is not going to bring it up.

RSUs Compound in Ways Startup Equity Doesn't

RSUs at big tech do not stop after year four. Annual refresh grants are standard at Meta, Google, Apple, and Amazon, stacking on top of unvested portions of prior grants.

A Meta E5 engineer starting with $300,000 in RSUs over four years will typically receive annual refreshes worth $100,000 to $150,000 per year based on performance. By year three, overlapping vesting streams from the new-hire grant and two or three refreshes mean total annual RSU income often exceeds the original grant rate. Liquid, in publicly traded stock, on a predictable schedule.

Most engineers compare year-one startup equity to year-one big tech RSUs. The right comparison is the four-year total at each place, accounting for dilution, exercise costs, taxes, and the probability of an exit that clears the liquidation stack. Big tech RSUs grow because of refreshes. Startup equity grows only if the company does, and only if it grows enough to clear every preference stacked above you.

Three in Four Startups Return Nothing to Investors

According to multiple analyses of venture outcomes, 75% of venture-backed startups never return invested capital to investors, let alone employees. Of startups that do exit, most are acquihires or small acquisitions where liquidation preferences absorb most of the proceeds.

Employee number one through five at a company that eventually IPOs has a real shot. Grants are large, the 409A at grant was low, and the liquidity event is transformative. About 2 to 5% of engineers in that position walk away with more than $1 million after tax. The other 95 to 98% have a great story at dinner parties.

After employee fifty, the math changes. Grants are smaller, the 409A is higher (so the spread from your strike to exit is narrower), dilution has accumulated, and the company needs a much larger exit for common shareholders to participate meaningfully.

The question is not whether startups can make you wealthy. They can. The question is whether this specific company, at this specific stage, with this specific liquidation stack, offers expected value that justifies the salary haircut.

Pre-IPO Tender Offers Are a Real Third Option

One thing that changed in the last few years: large late-stage startups now regularly run tender offers, where employees sell a portion of vested shares to investors at a negotiated price. OpenAI ran a $6.6 billion employee tender offer in late 2025. Anthropic has done several.

This does not change the math for most startups, which are not OpenAI. But if you are considering a well-funded late-stage company with a history of tender offers, it meaningfully reduces the "locked up forever" risk that makes startup equity so hard to value.

When the Startup Offer Actually Makes Sense

Early stage (first 20 to 30 employees). Clean cap table. A 1x non-participating liquidation preference rather than stacked participating preferred. An exercise window longer than 90 days. A company you would join regardless of the equity.

If you are joining for financial upside, stage matters as much as company. Series A or earlier with a reasonable cap table is a different bet than Series C with $200 million in liquidation preferences already stacked. Know the difference before you take the salary cut.

SpaceComplexity runs voice-based mock technical interviews with rubric-based feedback on the DSA and system design rounds that produce these offers in the first place.

The Short Version

RSUs are actual shares with no exercise cost, liquid at a public company, and compound over time with annual refreshes.
Startup options require cash to exercise, expire 90 days after you leave, and may trigger AMT before you can sell.
Dilution across multiple funding rounds will reduce your stated percentage by 40 to 60%.
Liquidation preferences mean an acquisition must exceed total investor capital before common stock gets anything.
75% of venture-backed startups return nothing to investors. Odds for employees are worse.
Startup equity makes financial sense early (sub-30 employees), with clean cap tables, at a company you would join regardless.
Late-stage companies with established tender offer programs are worth evaluating separately.