Lagging indicator
Why do some measures confirm a market move only after most of it has already happened?
In plain words
A lagging indicator is a measure, often an average of past prices, that changes direction only after the price it tracks has moved. It confirms a trend in hindsight rather than anticipating it, which is the price of reducing false signals.
Why it matters
Lagging indicators filter out noise, so fewer false turns are read as real. The cost is late entry and late exit: by the time such a measure confirms a decline, much of the move has already reduced a position's value, and it cannot tell you how much is left.
In a real week: ETH, week of 11 May 2026
ETH's prior four weeks before 11 May 2026 were +3.27%, +4.69%, -1.98% and +2.09%, so measures built on recent prices would have leaned positive going in. During the week of 11 May 2026, ETH opened at 2371.26 and closed at 2131.0, a -10.13% week, finishing in the lower third of the week range. Its low of 2091.48 came only at 2026-05-17 23:00 UTC (Sun), the last hour of the week, so any confirmation based on that week's prices became available only at the end.
A common mistake
Treating confirmation as prediction. A lagging indicator telling you a trend has turned does not tell you how much of the move remains ahead.