How to rebase daily closing prices

Divide every close by the first close so several price series can share one scale without pretending their dollar prices are comparable.

Written by Dean Shalem, published Sep 29, 2026, about 3 minutes to read.

A fan of daily panes keyed to one central spindle. A small MinerTerminal mark sits in the top-left corner. — Illustration: AI-generated artwork created for MinerTerminal in ChatGPT from original article concepts.

How this article reads

Signal. Divide every close by the first close so several price series can share one scale without pretending their dollar prices are comparable.
Mechanism and evidence. The "CleanSpark closes, rebased" chart, drawn from daily closing prices supplied by Polygon.io, which the sources list names.
Implication. The first close becomes one, and the last close becomes its ratio to that starting value.
Next catalyst. Where the figures update: the analysis page behind this example.
Sources. The sources list at the foot carries every document.

Corrected

Oct 3, 2026: The Mechanism and evidence line under How this article reads said the chart "CleanSpark closes, rebased" was drawn from daily closing prices supplied by Polygon.io and Yahoo Finance. It now says Polygon.io alone. A sentence in the worked example said the first and last closes come from a cached file that a reader cannot check against a documented endpoint. It now says Polygon.io supplied both, and that a reader can check them against its documented endpoint with a free key.
Oct 3, 2026: The worked example printed CleanSpark's first and last closes as 13 dollars each, then the divisions 13 / 13 = 1.0000 and 13 / 13 = 0.9713. It now prints each close to the cent, so on the data of Oct 2, 2026 the divisions read 12.89 / 12.89 = 1.0000 and 12.52 / 12.89 = 0.9713.
Oct 2, 2026: The Mechanism and evidence line under How this article reads said the chart "CleanSpark closes, rebased" was drawn from the filed sample the sources list carries. It now says the chart is drawn from daily closing prices supplied by Polygon.io and Yahoo Finance, which the sources list names.

The corrections log gives each change with the document that decided it.

Work through the figures.

CleanSpark closes, rebased

The first and last closes are shown as a ratio to the first close. As of Oct 21, 2026.

Method and sources

The first close becomes one, and the last close becomes its ratio to that starting value.

Covers: Jul 28, 2026 to Oct 20, 2026
Unit: ratio to the first close

Source: MinerTerminal analysis, computed from the cited source data

CleanSpark closes, rebased
Period	CleanSpark (ratio to the first close)
Jul 28, 2026	1 (derived)
Oct 20, 2026	0.63 (derived)

Rebase divides every close in a series by that series' own close on one chosen day. After the division, all series start at the same number and can share one chart.

We have 28 series in the price history, with 34,324 daily closes across all of them. CleanSpark carries 1,456 daily closes on file. In the indicator sample, its first close is 13.48 dollars and its last close is 8.43 dollars. Polygon.io supplied both of these closes. A reader can check them against its documented endpoint with a free key.

The base day is the first close in the sample. We divide every close by that base close. For the base day itself, the division is:

13.48 / 13.48 = 1.0000

The base day rebases to one. That is the point of the operation: every series, whatever its dollar price, starts at the same number.

For the last close in the sample, the division is:

8.43 / 13.48 = 0.6254

This is the rebased value for the last day. It is a ratio, not a dollar price. It says how many times the last close is relative to the base close.

We run the same division for every close in every series. Each series uses its own base close and gets its own set of ratios. The output is a rebased view: relative movements that share a common starting point.

We divided each close by its own series' close on the base day. Every series now begins at the same number. What the chart shows is relative movement from that shared start, not a dollar price.

Sources

Run the same figures on any company: the analysis page behind this example.