Vested RSUs and ESPP Shares: Deciding How Much Company Stock Is Too Much

Selling or holding vested RSUs is a different decision from the tax you already owe at vest. Many employers withhold at the flat 22% federal supplemental rate in 2026 (IRS Publication 15), which can fall short for a high earner. The real work is sizing one company’s stock inside your plan and deciding what each share is for.

How much company stock is too much?

There isn’t one right number, but there are three ways to measure it, and it’s easy to run only the first.

Schwab’s article on the risk of holding too much company stock (June 2026) draws the first line: “When a single stock accounts for more than 10% of a portfolio, overconcentration becomes a concern” (Schwab). That’s a general portfolio rule, and company stock is harder than most, because your paycheck rides on the same company.

First, vested company stock as a share of your investable assets. Say you hold $400,000 of one stock and $1.2 million of everything else. That’s 25%, and it’s the figure your brokerage screen makes easy to see.

Second, run it again with unvested RSUs counted as exposure. Say another $200,000 is still on the vesting schedule. Those shares aren’t yours until they vest (leave early or get laid off and the company keeps them), but while you’re employed they ride on the same stock. Now it’s $600,000 out of $1.8 million, a third of the picture.

Third, and this one never shows up on a statement, your paycheck, your bonus and your unvested grants all depend on the same employer. A bad stretch for the company can hit the stock, the bonus and the job in the same year.

Here’s my own working range, and it isn’t a rule: under 10% rarely needs a plan, 10% to 20% needs a reason you can say out loud, and past 20% you’re making a bet whether you meant to or not. Planners draw those lines in different places. Someone with $5 million outside the stock can carry more than someone with $500,000. Treat the range as a conversation starter.

Should I sell my RSUs when they vest, or hold them?

Three questions help.

First, would you buy this stock today, in this amount, with cash from your savings account? If not, holding is still a purchase decision. It’s just a quiet one.

Second, what is this share for? A share earmarked for a down payment in two years has a different job than one sitting in a retirement plan twenty years out.

Third, what does changing your mind cost? That means tax on any gain, your company’s trading windows (some companies limit when employees can sell), and wash-sale timing if you’re also selling something at a loss. The wash sale post covers that last one.

Here’s the part that gets tangled. The value of the shares on the day they vest was already taxed as wages. Sell that day and you’ve mostly just turned shares into cash at a price you’ve already paid tax on, so there’s little gain left to worry about. The tax question gets real for shares you keep, because they start building a gain on top of that. The lower long-term rate only applies to growth after the vest, and only after a holding period. That’s a long time to carry one company’s stock for a rate difference on the growth alone.

Does it matter if I sell all at once or in batches?

For shares sold at or near the vest price, mostly no. The tax comes out about the same whether you sell the lot today or a quarter at a time. Spreading starts to matter in three places.

First, the vest itself. You can’t push the income into another year, but you can manage the withholding. Payroll systems withhold at a set rate, not at your actual bracket, and the gap shows up in April.

What the payroll system applies in 2026	Figure	Why it matters on a vest
Flat supplemental withholding, up to $1 million in a calendar year	22%	Often what comes out of a vest, whatever your real bracket is
Mandatory supplemental withholding once supplemental wages in the year exceed $1 million	37%	Matters most in a year with a very large single vest
Social Security wage base	$184,500	The 6.2% Social Security tax stops once wages pass it, so payroll tax on a late-year vest can be lower

Source: IRS Publication 15 (Circular E), Employer’s Tax Guide, 2026.

If the withholding falls short, timing matters. Earlier in the year you can raise withholding. Later it gets harder, because the same dollars come out of fewer paychecks. The post on covering an RSU tax shortfall walks through why withholding and estimated payments aren’t treated the same.

Second, shares you’ve held that now carry a gain. Selling those across two or three tax years instead of one can keep a big gain from stacking on top of vest income. Which lots get sold changes how much gain shows up, and your brokerage’s default method may not be the one you’d pick, so ask your CPA how lot selection works on your account. Gifting appreciated shares to charity is another route, and the post on donating company stock covers the 2026 changes.

Third, ESPP shares, where the holding periods change how the gain is taxed. More on that next.

ESPP shares: sell at purchase or hold?

Same three questions, plus one wrinkle. The purchase discount is a built-in gain, so some people sell at every purchase to bank it and others hold. Selling right away gets you out of one-company risk but can mean part of the gain is taxed at ordinary rates. Holding through the longer holding periods can change that treatment, but you carry the stock the whole time. The lookback and both holding periods are laid out in how an ESPP actually works.

The riskiest option is the one nobody picks on purpose, which is letting shares pile up for years without making the call.

Start with a list of dated goals. A down payment, paying off a mortgage, a kid’s tuition, a leave of absence, a retirement date. Then match shares to them. Shares tied to a goal a few years out don’t have a strong reason to stay in a single stock. Goals decades away can tolerate more of it, if the concentration number above is one you’re comfortable with.

One client, a tech employee at a large company, holds about 30% of her total assets in a highly appreciated position and wants it spread out. What’s holding her back is the capital gains bill on selling. That’s a familiar tension. The tax is a number you can look up, and the concentration is a risk you can’t put a number on, so the tax gets the vote.

The way through is to put both on the same page. Size the tax, size the risk, then decide how many tax years and how many tranches it takes to get where the goals need you to be.

Where the coordination happens

Most of this sits across systems that don’t talk to each other: your payroll withholding, your brokerage lots, your CPA and your goals. That’s the work behind The San Diego H.E.N.R.Y. Strategy, where equity compensation gets planned alongside tax, cash flow and retirement instead of on its own.

Do you know what share of your investable assets is one company’s stock right now? If not, that’s a good first conversation, and it’s one we can have on a complimentary call.

Frequently asked questions

Should I sell my RSUs when they vest or hold them?

Neither is right by default. The tax on the vest is owed either way, so the useful questions are whether you’d buy that much of the stock today with cash, what the shares are meant to pay for, and what it would cost in tax and timing to change course later. If you’d rather not own that much of one company, selling at vest is the cleanest way to act on it, because there’s usually little gain on top of what was already taxed. Your CPA can confirm how that plays out for you.

Does it matter for taxes if I sell all my RSUs at once or in batches?

For shares sold at or near the vest price, the tax is about the same, since the vest value was already taxed as wages. Batches matter for shares you’ve held that now carry a gain, where spreading sales across tax years can change how much lands in one year. Ask your CPA to model it.

Should I sell my ESPP shares right away or hold them?

It’s a trade between possible tax savings and concentration. Selling right after purchase locks in the discount and removes one-company risk. Holding through the longer holding periods can change how part of the gain is taxed, but you carry the stock the whole time. The ESPP post covers the holding periods.

Do you get taxed twice on RSUs?

Not on the same dollars, if the numbers are reported correctly. The value of the shares at vest is taxed as wages, and that value becomes your cost basis. When you sell, the gain or loss is measured from that basis, so only the change after the vest is taxed again. Brokerage forms don’t always show the full basis, so compare yours with your vest records and ask your CPA.

How long should I hold my ESPP shares?

There isn’t one answer. The tax holding periods (covered in the ESPP post) set the earliest dates that change how the gain is taxed, but how long you hold also decides how much of one company’s stock you carry. Compare the tax difference, in dollars, with the stock you’d be holding to get it, and bring both numbers to your CPA.

Intuit: the RSU and ESPP guide for Intuit employees
Qualcomm: the 401(k) match and equity guide for Qualcomm employees
Northrop Grumman: the benefits guide for Northrop Grumman employees, including the ESPP decision after the purchase

BAS Financial is an independent entity and is not affiliated with, endorsed by, or sponsored by Intuit, Qualcomm Incorporated or Northrop Grumman.

Sources: IRS Publication 15 (Circular E), Employer’s Tax Guide, 2026. Schwab, The Risk of Holding Too Much Company Stock, June 5, 2026.