Calendar rebalancing
Returning weights to target on dates fixed in advance — quarterly, half-yearly or annually — regardless of how far the portfolio has drifted.
How to read the number
Its virtue is predictability: the date is known ahead of time, the decision does not depend on the news flow and it requires no daily watching.
When the metric lies
Between dates the drift is unbounded: a large move right after one review lives in the portfolio until the next. Rare reviews save on costs at exactly that price.
Also known as: periodic rebalancing