Stock Price Change Calculator
From buy price to P&L — see exactly what a percentage move means for your money.
Understanding Stock Percentage Moves
When a stock drops 10%, many investors think "I just need a 10% bounce to break even." Wrong. You need 11.1%. This asymmetry gets worse with bigger drops — a 50% crash requires a 100% rally to recover.
Common Percentage Thresholds in Trading
| Move | Term | What It Means |
|---|---|---|
| −5% | Pullback | Normal, healthy dip in an uptrend |
| −10% | Correction | Official market correction; common ~1×/year |
| −20% | Bear market | Official bear market territory |
| −30%+ | Crash | Severe decline; occurs ~2-3× per decade |
| +10% | Rally | Strong rebound from lows |
| +20% | Bull market | Official new bull market |
The 10% Rule in Investing
Stop-loss at 10%: Many traders use a 10% stop-loss rule — automatically selling if a position drops 10% to limit further losses.
10% annual return: The S&P 500 has averaged ~10% annual returns historically (before inflation). This is the benchmark most investors compare against.
10% position sizing: A common risk management rule: never put more than 10% of your portfolio in a single stock.
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