Accumulation is a happy problem in disguise. You build a position, it runs, and suddenly it is a huge chunk of your whole account. A coin that was five percent of your portfolio can become forty percent after a big move. That is a win, but it is also a concentration risk that can undo you in one bad day.
Rebalancing is trimming that oversized winner back toward a size you are comfortable with. You are not calling the top and you are not selling in a panic. You are just taking some off so that no single position can decide your fate. The rest keeps running, and you sleep at night.
The math is plain. Say you hold a ten thousand dollar account and one coin has grown to be forty percent of it, so four thousand dollars. You decide your comfortable target for one name is twenty-five percent, or two thousand five hundred dollars. To get back to target, you sell fifteen hundred dollars worth. You keep most of the position and take real profit off the table at the same time.
When a winner grows into an outsized share of your account, trim it back toward a target weight. Rebalancing takes profit and cuts concentration risk without needing you to call the top.
Tip. Set your target weight before a coin ever runs, so the trim is a rule and not an agony. Rebalancing on the way up pairs perfectly with taking profit in tiers: you sell a little into strength and let the rest ride.