Research · Altcoins · Strand B

ETH behaviour during Bitcoin bear phases

Bear phases are where the comparison between two assets is most often asserted and least often measured properly. This page sets out how a bear phase is defined, how drawdown depth and duration are compared across two assets, and why a deeper decline in one asset is not evidence about the other's cause.

Last reviewed 2026-09-21Source: CoinGecko historical price data; Bitcoin cycle definitions from this site's cycle recordMethod and comparison only. No drawdown percentage is asserted.

Defining a bear phase and a drawdown

A bear phase is the contraction half of a market cycle: the period from a cycle high to the subsequent cycle low. A drawdown is a narrower and more precise measure: the decline from a running peak to the lowest point that follows it, expressed as a percentage of that peak. The two are related but not identical. A cycle's contraction contains many drawdowns, and the maximum drawdown within a contraction is the deepest of them. This page uses the maximum drawdown within each defined phase, because it is the measure that can be computed unambiguously from a price series.

Duration is the second dimension, and it is the one most often omitted. A decline that is deep but brief and a decline that is shallow but long are different experiences for a holder, and a comparison that reports only depth hides the difference. Duration can be measured from peak to trough, or from peak to the recovery of that peak. The second is the more demanding measure and the one that matters to a holder who bought at the top. The Recovery Time page covers that measure for Bitcoin, and the Drawdown Explained page defines the terms.

Both measures are sensitive to the window chosen. A drawdown computed from a daily close series will differ slightly from one computed from intraday extremes, and the choice has to be stated. This page uses daily closes, which understates the true intraday extreme but is consistent across both assets and reproducible from the published series.

Comparing depth and duration across two assets

The dimensions on which ETH and BTC drawdowns can be compared within a shared bear phase, and what each dimension does and does not show.
Dimension	How it is measured	What a difference shows
Drawdown depth	Peak-to-trough decline as a percentage of the peak, daily closes	How much more or less the asset fell; not why it fell
Drawdown duration	Calendar days from peak to trough	How long the decline persisted; not how long a holder waited to break even
Time to recovery	Calendar days from peak to the first close above that peak	The full cost to a holder who bought at the top; the more demanding measure
Timing of the trough	Whether the two assets bottomed in the same period	Whether the declines were synchronised; not which asset led
Relative drawdown	The ratio of the two assets' prices at peak against at trough	Relative resilience over the phase; not a statement about either asset's cause

Last reviewed 2026-09-21Source: Method description; daily close series from CoinGeckoNo percentage is stated; the table defines the comparison dimensions.

The most common error in this comparison is to treat a deeper drawdown in one asset as evidence that the other asset's decline caused it. A deeper decline is consistent with higher sensitivity to a common factor, with a thinner liquidity base, with a larger speculative component in the holder base, or with an asset-specific negative event. The drawdown figure cannot separate those explanations. It reports the depth of the fall and nothing more.

A second error is to compare drawdowns across phases rather than within them. If ETH's deepest drawdown occurred in a different period from BTC's, comparing the two figures describes two different market environments rather than two assets under the same conditions. The comparison is only meaningful when both assets are measured over the same window, which is why this page fixes the phase boundaries first and measures both assets within them.

The synchronisation of troughs is itself informative. When two assets bottom in the same period, that is consistent with a common factor driving both. When they bottom at different times, something asset-specific was at work. Neither observation establishes causation, but the second is harder to explain with a pure common-factor story, and it is worth noting when it occurs.

Why the comparison is weaker than it looks

The number of completed bear phases in Ethereum's history is small, and each is a single observation. A comparison across three or four phases describes those phases. It does not establish that one asset is structurally more volatile than the other, because the sample is too small to separate a structural difference from period-specific conditions.

The two assets also differ in ways that affect drawdown mechanics independently of any relationship between them. Their supply schedules differ, their holder bases differ, and the instruments through which they are traded differ. A deeper drawdown in one may reflect the leverage available in its market rather than anything about the other asset. For the volatility measure that underlies this, see Volatility Explained.

Dataset, period, method and limitations

Dataset: Daily ETH and BTC closing prices from CoinGecko. Bear phase boundaries are taken from this site's own cycle record.
Period: From Ethereum's public trading history to the last-reviewed date stated above, covering the completed Bitcoin cycles within that span.
Method: Within each defined bear phase, the maximum drawdown is computed from daily closes as the peak-to-trough decline as a percentage of the peak. Duration is measured in calendar days from peak to trough, and time to recovery from peak to the first close above it. Both assets are measured over identical windows.
Limitations: Daily closes understate intraday extremes. The sample of completed phases is very small, so no structural difference between the assets can be established from it. A deeper drawdown is consistent with several explanations and does not identify a cause.

What this page does not claim

This page does not state a drawdown percentage or a recovery time for either asset. It does not claim that Bitcoin's decline caused Ethereum's, and it does not treat a deeper drawdown in one asset as evidence about the other's fundamentals. It does not generalise from a small number of completed phases.

Sources and references

Every source below is named and linked. Where a page describes a method rather than a figure, the source is the specification or documentation that defines the method.

Ethereum historical data. CoinGecko, www.coingecko.com/en/coins/ethereum/historical_data: the ETH daily close series used for the drawdown calculation.
Bitcoin historical data. CoinGecko, www.coingecko.com/en/coins/bitcoin/historical_data: the BTC daily close series used for the same calculation.
Bitcoin drawdowns. Bitcoin Data Guide, bitcoindataguide.com/drawdowns: the site's own drawdown record, for the Bitcoin leg of the comparison.
Community data. Coin Metrics, coinmetrics.io/community-network-data/: an independent series used to cross-check the price inputs.