The zero line is the break-even. Any BTC price where the curve is above zero means the deal adds sats-per-share for common shareholders - accretive. Below zero means it costs them - dilutive. The curve crosses zero at the break-even price.
Why delta? The previous two-curve chart showed absolute CEBE before and after a deal. For Strategy - with 818K BTC - a +3K sat change is invisible because both curves overlap at the same scale. The delta chart normalizes the signal: the shape of the deal is visible regardless of company size.
Why does the curve slope? Fiat-denominated claims (USD, JPY, GBP, etc.) compress in BTC terms as BTC price rises. A ¥23.6B preferred issuance represents fewer and fewer BTC at higher prices, so its drag diminishes. BTC-denominated claims stay flat regardless of price. The slope of the delta curve reflects the currency mix of new claims relative to BTC acquired.
How to pull these numbers from an 8-K
BTC Bought: Look in the 8-K exhibits (Item 7.01 or 8.01) for "bitcoin acquired" or "purchased X bitcoin." Use the total BTC amount, not a weighted average.
Shares Issued: Common shares only. Find "shares of common stock" or "shares issued" - exclude preferred, warrant, or convertible shares unless they're converting to common on the deal date.
Claims Added: For preferred issuances, use the face/par value (not the issue price). For convertible notes or bonds, use the principal amount. For ATM equity with no debt component, leave this at zero.
Currency: Use the native currency of the instrument - JPY for Metaplanet bonds, GBP for TSWCF bonds, USD for Strategy preferred. The engine handles compression correctly for each currency.