A leveraged position has two numbers worth following: the market value of the investment and what remains yours after the loan. The price can fall while the principal owed stays unchanged. The reduction then comes out of your equity.
The title’s 20% and 40% use different denominators. One measures the fall in all the shares; the other measures the loss against your own starting contribution. The example below follows the dollars before adding interest or margin requirements.
Follow what remains after the debt
Consider a hypothetical purchase with no dividends, fees, taxes or interest for the moment. You contribute $10,000 and borrow another $10,000. The shares initially cost $20,000.
Your equity is the shares’ market value minus the outstanding loan. It starts at $10,000. Equity is a residual claim, rather than a separate pile of cash that stays safely outside the investment.
If the share price falls 20%, the position is worth $16,000. Subtract the unchanged $10,000 loan and your equity is $6,000. You have lost $4,000 out of your original $10,000: 40%.
With no borrowing, $10,000 invested in the same shares would fall to $8,000. The percentage price move is identical, but only half as many dollars were exposed to it.
The SEC’s explanation of margin accounts describes this amplification in both directions. In our example, a 20% rise instead produces $24,000 of shares. After repaying the principal, $14,000 remains: a 40% gain before costs. Borrowing changes the size of the result without changing which way the shares move.
What “two-to-one” measures
At purchase, investment value divided by equity is $20,000 ÷ $10,000, or two. That is the starting leverage ratio. A 1% move in the original $20,000 position is $200, equivalent to 2% of the initial equity.
For this fixed position and unchanged principal, the return on starting equity before costs equals the investment’s percentage return multiplied by two. That arithmetic assumes no extra deposits, withdrawals or trades.
The ratio itself does not stay at two after prices move. Following the 20% fall, $16,000 of shares sits above just $6,000 of equity: about 2.67 to one. Another 1% drop from that new share value would cost $160, about 2.67% of the equity then remaining. The original percentage comparison and the account’s current vulnerability answer different questions.
Interest can turn a flat price into a loss
Now suppose the hypothetical $10,000 loan costs $1,000 over one year. This is an invented round interest charge, not a broker quote. Assume it is paid at the end, with no other costs or cash flows.
The amount left after selling is the shares’ value minus $11,000: $10,000 of principal and $1,000 of interest.
| Share-price change | Shares at sale | Money left after principal and interest | Return on initial $10,000 |
|---|---|---|---|
| Up 20% | $24,000 | $13,000 | +30% |
| Unchanged | $20,000 | $9,000 | −10% |
| Down 20% | $16,000 | $5,000 | −50% |
These are alternative outcomes of one simplified purchase, not successive periods or forecasts. The flat-price row isolates the borrowing cost: the shares lose nothing, yet your money falls by $1,000.
Breaking even requires the $20,000 position to gain $1,000, or 5%, in this example. The assumed charge equals 10% of the amount borrowed; it does not equal 10% of the whole investment. Actual interest accrual, changing rates, fees, taxes and distributions would change the result. The SEC’s bulletin explains that loan interest reduces investment returns.
A margin requirement can end the wait
The table assumes you can hold until the chosen sale date. A U.S. brokerage margin account introduces another constraint: the assets secure the loan. FINRA explains that a call can follow falling account value, a trade that creates a deficit, or a higher house requirement.
Keep the first example’s interest-free numbers and imagine a broker requires equity equal to 40% of the shares’ current value. This is an illustrative house requirement, not a universal threshold. After the fall, the account has $6,000 of equity against $16,000 of shares: 37.5%. It is below that assumed requirement even though the shares are still worth more than the principal owed.
FINRA says firms can liquidate holdings without first issuing a margin call, and the customer need not get to select what is sold. Its explanation also notes that house requirements can increase without advance written notice. A plan to wait for a recovery therefore depends on the lender’s terms as well as the investment’s price.
Losing the deposit need not settle the loan
Return to the one-year example with $11,000 due. A hypothetical 60% fall takes the $20,000 position down to $8,000. Selling everything leaves $3,000 still unpaid. Your original $10,000 is gone and another $3,000 is owed, for a total loss of $13,000 before any other costs.
A real broker might liquidate earlier; this is a shortfall calculation, not a prediction of when a broker would act. The SEC’s leveraged investing bulletin confirms that margin losses can exceed the investor’s initial contribution.
The examples have added one constraint at a time: price movement, changing leverage, interest, a margin requirement, then a remaining debt after sale. Keep those calculations separate before combining them for an actual arrangement. A lender’s contract and the money available to meet it can matter alongside an investment’s value, as the missed-capital-call example illustrates. None of the calculations predicts which way a market will move.
