Selling is harder than buying — and the research shows the average investor does it at the wrong moments (after a fall, in panic). Three reasons survive scrutiny:
You bought for a reason — growing profits, a strong brand, a healthy balance sheet. If those fundamentals deteriorate structurally (not one weak quarter), the reason to own is gone.
Trimming a position that grew too large for your diversification is discipline, not market timing — it historically reduced risk without costing return.
Money needed within a few years should leave stocks step by step — on calendar dates you chose in advance, not on price levels.
"The price dropped." Drawdowns of 10-30% are a statistical part of owning stocks; those who sold after the fall historically missed the recovery — the most expensive mistake in investing.