Bitcoin dominance and altseason

The first reason is that the measure is a share, not a level. A reader who wants to know whether altcoins are rising needs a price or a return, and the share does not supply one. The two questions — how the market is divided, and which way it is going — are independent, and a single number cannot answer both.

The second is that the denominator is not a fixed basket. The set of tracked assets changes as tokens are listed, delisted and reweighted, and the supply estimates behind each one are themselves estimates. A provider that adds a large new asset to its universe will move the share without any trade occurring. That makes long-run comparisons of the share across providers unreliable, and it is a reason to prefer a breadth measure when the question is whether outperformance was widespread.

The third is that the share is a market-wide aggregate, so it cannot distinguish a broad rotation from a narrow one. If a single very large non-Bitcoin asset rises sharply, the share falls, and the breadth measure may barely move. The two measures disagreeing is informative rather than contradictory: one is telling you about the division of value, the other about how many assets participated. Reading them together is more useful than reading either alone, and the timing page uses both to date the episodes.

The central limitation is that this page describes a relationship between two published series without asserting a correlation coefficient, a beta or a return. Those quantities depend on the window chosen, the provider used and the treatment of the supply estimates, and a figure computed here could not be verified against a source. The page therefore states the structure of the relationship and leaves the estimation to a reader with a stated dataset.

The second is that dominance and breadth are not independent observations. Both are computed from the same market prices over overlapping windows, so a period that registers as altseason on one will tend to register on the other. Treating their agreement as corroboration would double-count a single body of evidence.

The third is the familiar distinction between association and cause. A falling share and a period of broad altcoin outperformance can both be produced by a common factor — a change in risk appetite, a shift in the cost of capital — without either causing the other. Nothing in the dominance record separates those explanations, and no page on this site claims that Bitcoin caused an altcoin's move on the strength of co-movement alone.