Day 0 is the day each last closed below the anchor. Both in dollars on one axis from zero — readable only because both start at the same price, which is the whole point of aligning them. Bitcoin's peak and the bottom of what followed are marked; narrow the window to see the early days, which is where Zcash currently is. Log makes those legible but cannot reach zero, so it flatters the shape.
Each as a multiple of its own anchor, divided. 1.0 is the same point on the same day; above is Zcash running hotter than Bitcoin did. Multiples rather than prices, because the two anchors sit a few dollars apart. Same x-axis as the chart above, so the line stops where Zcash's run does rather than being stretched across the width.
One run against one run. A sample of two is a shape, not a base rate — and the 2017 curve is famous precisely because it was unusual.
The anchor is a round number, not a level. Move it above. A conclusion that survives $500 and $1,000 might be about the assets; one that only works at $800 is about the anchor.
The assets are not comparable where it matters. Different issuance, float and liquidity, and a market structure — regulated venues, deep derivatives, spot ETFs — that did not exist in 2017.
The drawdown is part of the analogy. Bitcoin peaked at day 338 and gave back most of it. Using this chart for the upside means using it for that too, which is why the peak and the bottom sit on the same line as the run and the default view is the whole cycle.
Day 0 is the day after each asset's last daily close below the anchor, taken from the most recent run: latest day at or above the line, then walk back to the last day under it. Not the first close above it — Bitcoin first closed over $800 on 2016-12-21, gave it back on 2017-01-11, and only then went, so a first-crossing anchor would have to pick one of those arbitrarily.
Walking back from the present rather than from the all-time high matters for both assets, in opposite directions. Zcash's highest price in this data is its launch-day spike of 28 October 2016 — four figures on almost no liquidity, then two years down — and no priced day sits below $800 before it, so an all-time-high rule finds no Zcash run at all. Bitcoin at a $5,000 anchor ran to $19,345 and back under $5,000, a completed round trip that a “last close below the line, full stop” rule erases entirely.
Bitcoin is searched only within its 2017 cycle (2015-01-01 to 2018-12-31). Over all history the last close below $5,000 is the March 2020 crash, and an unbounded anchor would quietly align Zcash against whichever Bitcoin cycle happened to match the number.
Prices are daily USD closes, the same series every other chart here uses. Days are counted from the anchor date, so a gap in the feed leaves a gap in the line rather than shifting everything after it sideways. Both series run up to 1,000 days past their anchor, or to the end of Bitcoin's cycle window, whichever comes first.