Plain-English definition
A depeg is a sustained move away from an instrument's intended reference. A fixed USD token, a euro token, an accumulating-NAV unit, and a rebasing yield token do not share the same mechanical test.
A large or persistent drift can reflect redemption, backing, market liquidity, venue access, FX timing, or source problems. It is a stress observation that needs investigation, not a verdict by itself.
Why it matters
Depeg matters because crypto markets can look precise while still being shallow, crowded, or poorly sourced. A useful read is not just the number. It is the number, the size behind it, the context around it, and the part it cannot explain.
Simple example
A simple Depeg example is a reader comparing two venues with the same headline price but different depth. The deeper venue can absorb more capital before the trade, peg, or yield reading starts to move against the user.
How Bathymark uses this term
Bathymark uses Depeg to translate open market data into live liquidity readings. When the term touches a live page, the reading links back to the relevant chain, protocol, stablecoin, DEX, perps, or Signal so the source remains checkable.
Common mistake
The common mistake is treating Depeg as a complete signal by itself. Bathymark treats it as one instrument: useful when read beside liquidity, source, size, and what the number cannot prove.