Costco (COST) Stock Concentration Calculator

Calculator · free · no signup · COST

Quantify Costco concentration risk. Drawdown impact at 30 / 50 / 70%, with the tax-aware trade-off between selling down and hedging.

Beta · invite-only · AlphaLatitude Inc. · Free Tools

Your inputs

Adjust — results update instantly.

Position & portfolio

Default. Adjust to test.
35%
Default. Adjust to test.
20%
10%

Tax

67%
Highly concentratedLong-term
If 30% drop
−$150,000
If 50% drop
−$250,000
If 70% drop
−$350,000

Most fee-only advisors target ≤10% in any single name. You're at 67%.

Estimates only. Not financial advice.

Most sensitive to: Expected market return (±10% on this input swings best-plan wealth by ±$190,508).

Cost of fully de-concentrating

All three plans sell to 0% (no hedge).

Tax
Wealth (3y)$956,485
+$33,417 vs.

Tax
Wealth (3y)$994,174
+$71,106 vs.

Tax
Wealth (3y)$1.04M
+$112,490 vs.

Sensitivity. If your expected position return drops below 19.6%/yr, lump-sum (sell everything today) beats every spread plan above.

Have multiple RSU vest lots? The RSU Lot Order Calculator picks which lots to sell first, and on which dates, to divest at the lowest computed tax.

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Toggle below — chart updates live. Sell buttons show the slice.
Sell over 1 yearSell over 2 yearsSell over 3 yearsCustom
$712,500$815,995$919,489$1,022,984$1,126,478Yr 0Yr 1Yr 2Yr 3
Year 1
Year 2
Year 3
Tax$200,753
Hedge cost$37,676
Wealth at Y3$1,046,371
Vs. best fixed plan+$10,813

Tech / Software single names hit a 50%+ peak-to-trough drawdown in roughly 1 of every 5 rolling 3-year windows over 2014–2024. Even mega-caps aren’t exempt.

Tax brackets: 2026 · Estimates only — not financial advice.

Estate note. Heirs receive a stepped-up basis at death (§1014), eliminating built-in gain on inherited shares. Older holders who plan to bequeath rather than sell may rationally never de-concentrate.

You sized one position's risk. The beta integrates hedging, sell-down, and tax timing into one optimized plan.

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Related calculators: Protect Your Stock Calculator · RSU Lot Order Calculator · Equity Funding Plan Calculator

About Costco

Costco (COST) is a public Other company, incorporated in Washington and headquartered in Issaquah, WA.

Equity grants at Costco typically include restricted stock units (RSUs).

Costco Wholesale Corporation is an American multinational corporation that operates a chain of membership-only big-box warehouse club retail stores. As of 2025, Costco is the third-largest retailer in the world, and as of August 2024, the world's largest retailer of beef, poultry, organic produce, and wine, with just under a third of American consumers regularly shopping at Costco warehouses. As of 2026, Costco is ranked 12th on the Fortune 500 rankings of the largest United States corporations by total revenue, and is also ranked as the largest grocery retailer in Canada.

Source: Wikipedia (CC BY-SA 4.0)

Jim Sinegal and Jeff Brotman opened the first Costco warehouse in Seattle in 1983, and the company merged with Price Club, the format's originator, in 1993. The economics are unusual: gross margin on goods is held deliberately low, roughly eleven percent, and membership fees supply the majority of operating profit, which aligns the company with members rather than suppliers. Kirkland Signature private label carries a large share of sales. Employee pay and retention run well above retail norms. Headquarters are in Issaquah, Washington.

Sources: costco.com · en.wikipedia.org

Equity comp at Costco

  • RSUs use single-trigger vesting: shares become yours as each portion vests on schedule, and the value is taxed as ordinary income at that point. No IPO or acquisition is required.

Researched 2026-08-17.

OptionsAhoy is an independent tool and is not affiliated with, endorsed by, or sponsored by Costco.

If a meaningful share of your net worth sits in COST, concentration risk is the question. This calculator quantifies drawdown impact at 30 / 50 / 70%, and the trade-off between selling down (tax cost now) versus hedging (option premium drag), auto-filled with COST's option-implied volatility.

All Costco tools → · Use the generic Stock Concentration Calculator for any company. Diversifying multiple RSU lots? See the lot-by-lot sell order →

Costco equity questions

How much COST stock is too much?
There is no single threshold, but the larger the share of your net worth in one stock, the more a single bad year can set back your plans. The calculator above quantifies the drawdown impact at 30, 50, and 70 percent for your COST position and weighs selling down (which triggers capital-gains tax now) against hedging (which costs option premium).
Does Costco grant ISOs, NSOs, or RSUs?
Equity compensation at Costco typically takes the form of restricted stock units (RSUs). Restricted stock units are taxed as ordinary income when they vest.
Do Costco RSUs use double-trigger vesting?
No. Costco restricted stock units (RSUs) use single-trigger vesting: each tranche becomes yours as it vests on schedule, taxed as ordinary income at that point, with no liquidity event required.
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OptionsAhoy plans your Costco equity alongside hedging, vesting, and de-concentration, across bullish, neutral, and bearish market scenarios. Free during beta.

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