Biogen (BIIB) Stock Concentration Calculator
Calculator · free · no signup · BIIBQuantify Biogen concentration risk. Drawdown impact at 30 / 50 / 70%, with the tax-aware trade-off between selling down and hedging.
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Adjust — results update instantly.Position & portfolio
Tax
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).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.
Build your own plan
Toggle below — chart updates live. Sell buttons show the slice.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.
Request beta access →Related calculators: Protect Your Stock Calculator · RSU Lot Order Calculator · Equity Funding Plan Calculator
About Biogen
Biogen (BIIB) is a public Pharma/Biotech company, incorporated in Delaware and headquartered in Cambridge, MA.
Last close: $225.88 per share (as of 2026-10-01).
Equity grants at Biogen typically include restricted stock units (RSUs).
Biogen Inc. is an American multinational biotechnology company based in Cambridge, Massachusetts, United States specializing in the treatment of neurological diseases. The company's primary products are dimethyl fumarate (Tecfidera), diroximel fumarate (Vumerity), interferon beta-1a (AVONEX), peginterferon beta-1a (Plegridy), and natalizumab (Tysabri), all for the treatment of multiple sclerosis ; nusinersen (Spinraza) for the treatment of spinal muscular atrophy ; omaveloxolone (Skyclarys) for the treatment of Friedreich's ataxia ; tofersen (Qalsody) for the treatment of ALS; and dimethyl fumarate (Fumaderm) for the treatment of severe plaque psoriasis. The company also produces 5 biosimilars and has collaborations with Genentech for several drugs.
Source: Wikipedia (CC BY-SA 4.0)
Walter Gilbert and Phillip Sharp, both later Nobel Prize winners, co-founded Biogen in 1978 with Kenneth Murray, Heinz Schaller, and Charles Weissmann, one of the first companies built around recombinant DNA research. Headquartered in Cambridge, Massachusetts, Biogen develops treatments for neurological and neuromuscular diseases, including multiple sclerosis drugs and Leqembi, an Alzheimer's therapy sold with partner Eisai. In March 2026 Biogen agreed to acquire Apellis Pharmaceuticals for $5.6 billion in cash, a deal that closed in May 2026 and added two FDA-approved drugs, Empaveli and Syfovre, which generated a combined $689 million in 2025 revenue.
Sources: biogen.com · statnews.com · cnbc.com
Equity comp at Biogen
- 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 Biogen.
If a meaningful share of your net worth sits in BIIB, 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 BIIB's option-implied volatility.
Example: 5,000 BIIB shares at $225.88 is a $1,129,400 position. A 30% drawdown costs $338,820; a 50% drawdown costs $564,700; a 70% drawdown costs $790,580. The calculator quantifies the trade-off between selling down (immediate capital-gains tax) and hedging (option premium drag) using BIIB's option-implied volatility and your cost basis.
All Biogen tools → · Use the generic Stock Concentration Calculator for any company. Diversifying multiple RSU lots? See the lot-by-lot sell order →
Biogen equity questions
- How much BIIB 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 BIIB position and weighs selling down (which triggers capital-gains tax now) against hedging (which costs option premium).
- Does Biogen grant ISOs, NSOs, or RSUs?
- Equity compensation at Biogen typically takes the form of restricted stock units (RSUs). Restricted stock units are taxed as ordinary income when they vest.
- Do Biogen RSUs use double-trigger vesting?
- No. Biogen 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 Biogen equity alongside hedging, vesting, and de-concentration, across bullish, neutral, and bearish market scenarios. Free during beta.