A concentrated position is a single holding — most often one company’s stock — large enough relative to an investor’s total portfolio or net worth that its price movement, rather than the broader market, determines most of the portfolio’s risk and return.
In plain terms
Most investors arrive here by accident rather than by choice: equity compensation, a founder’s own company, or one winning bet that was never trimmed. There is no regulatory line that turns a holding into a “concentrated” one — it is a continuum — but wealth managers commonly flag a single name once it passes somewhere around 10% of investable net worth, because at that scale one company’s earnings call can move a household’s balance sheet more than the stock market does.
How it works
A single stock behaves nothing like the index it sits inside. Between July 2014 and July 2024, the average S&P 500 constituent carried annualized volatility of about 31.5%, versus 17.7% for the index itself — roughly 1.5 times as volatile for a similar average return, because diversification cancels out company-specific risk without canceling out market-wide return. That asymmetry compounds on the way down: a holding that falls 20% needs to gain 25% just to get back to even, and one that falls 50% needs to double.
Concentration shows up differently depending on how the stock was acquired. An employee sitting on vested RSUs or exercised options can generally sell on the open market, subject only to the company’s own trading windows. A founder, director, or officer selling restricted or control stock under U.S. securities law instead runs into SEC Rule 144’s volume limit — in any three-month period, the greater of 1% of the shares outstanding or the stock’s average weekly trading volume over the prior four weeks — plus a Form 144 filing once sales pass 5,000 shares or $50,000. Retirement-plan savers get a narrower, statutory fix: under 26 U.S.C. § 401(a)(35), a 401(k) participant with at least three years of service has the right to move employer-stock holdings into other options, a rule written into federal law after Enron-era 401(k) losses and effective for plan years beginning on or after January 1, 2011.
The numbers
- Common advisory flag: roughly 10% of net worth in a single security — practice, not law.
- Volatility gap: ~31.5% average single-stock volatility vs. ~17.7% for the S&P 500, measured 2014–2024.
- Drawdown math: a 30% loss needs a 43% gain to recover; a 50% loss needs 100%.
- Rule 144 affiliate volume cap: the greater of 1% of outstanding shares or four-week average trading volume, per three-month period.
- 401(k) diversification right: available after three years of service, required for plan years beginning on or after January 1, 2011.
What people get wrong
That the fix for concentration is always to sell. For an insider under a trading blackout, an early employee without a liquid market, or anyone for whom selling would trigger a large tax bill, an outright sale is often not available — which is why a toolkit exists instead: 10b5-1 trading plans to sell on schedule, SBLOCs to borrow against the position, and exchange funds to swap it into a diversified basket. The less obvious misconception is that concentration is unusual: across nearly a century of U.S. market history, a small fraction of stocks have driven most of the market’s wealth creation above Treasury bills — every diversified portfolio’s return is itself concentrated in whichever handful of names turn out to matter, and the investor’s only real choice is whether that concentration is chosen or inherited.
Related
Read more: Tech Wealth: How Founders and Investors Live Differently · Equity Compensation: RSUs, ISOs, and the Tech Wealth Engine
See also: Exchange fund · SBLOC · 10b5-1 plan