How to read it

DXY measures the dollar against a basket of six currencies - mostly the euro, with the yen, sterling, Canadian dollar, krona and franc making up the rest. It is a measure of the dollar's strength, not a price, and that changes how it should be combined with BTC.

The second panel multiplies rather than divides. On the stocks page BTC/index is right because both are prices and dividing cancels the dollar out. Here, if the dollar strengthens while BTC's dollar price holds flat, Bitcoin has actually gained against every other currency - so the adjustment is BTC × (DXY ÷ 100). Dividing would double-count dollar strength instead of removing it, and would push the line the wrong way on every dollar rally.

The third panel scores DXY itself rather than the series above it. That's a deliberate break from the other cross-asset pages: Bitcoin's volatility is an order of magnitude larger than the dollar's, so a z-score of the trade-weighted series would be within noise of a plain BTC z-score - a chart you already have. Scoring the dollar answers something none of the other panels do, namely whether the dollar is itself stretched.

The fourth panel is the claim most people are actually making when they pair these two: that BTC goes up when the dollar goes down. It is a 90-day correlation of daily returns, so 0 means they move independently and negative means the inverse relationship is showing up. Worth knowing before leaning on it: the correlation has been negative on 60% of days with data. It is a tendency, not a rule, and it spends real stretches on the wrong side of zero.

Invert DXY on the first panel flips the dollar axis so an inverse relationship reads as two lines moving together. It reverses the axis only - the data is untouched and the tooltip still reports the true level. Use it to check the relationship by eye rather than taking it on faith.

BTC daily closes from Coin Metrics; DXY from Yahoo Finance (DX-Y.NYB), aligned to DXY's trading days. The 252-day and 90-day windows match the BTC vs Stock Markets and BTC/Gold pages so all three read the same way. Not financial advice.