Every figure should say where it came from
2 min read
A balance read from a chain, a balance read from an exchange, a balance replayed from a statement and a balance typed in by hand are four different kinds of claim — and a total that mixes them silently is not one number.
Portfolio totals feel like measurements. Most of them are partly estimates, and the parts are not labelled. That is fine right up until you make a decision on one.
Four kinds of claim
Holdings reach a tracker by different routes, and the routes are not equally trustworthy. It is worth being explicit about the order:
- Read from a chain by address. The strongest: the ledger is public and was queried directly.
- Read from an exchange with your own read-only key. Strong: the venue itself reported it, authenticated as you.
- Replayed from a transaction statement the venue produced. Weaker: it was true when the statement was exported.
- Typed in by hand. Weakest: it is as current as the last time someone remembered to update it.
Fetched quantities and stored quantities
The bottom two share a property the top two do not. Their quantities are stored rather than fetched, so they are frozen until you replace them. Only their prices move.
That produces a specific and quite convincing failure. A manually entered holding you sold six months ago keeps appearing, and it keeps being repriced, so it looks alive — the figure changes every day. Movement reads as freshness. It is not: the price is current and the quantity is stale, and nothing about the display distinguishes that from a position that is genuinely still open.
One methodology for price
There is a second way a total quietly stops meaning anything: pricing the same asset two different ways. If holdings from one source are priced by one method and holdings from another source by another, then two identical amounts of the same coin can carry different values inside the same total, and the sum is not a quantity of anything.
Quantities can come from anywhere — that is what having several kinds of connection means. Price has to come from one methodology, applied to every holding regardless of where its quantity was read. Then adding the pieces together is a legitimate operation.
What to ask of any tracker
Can you tell, from the screen, which of your holdings were measured and which were remembered? If not, the total is a blend of both and you cannot know in what proportion. That is the question this product is built around, and the reason every figure in it carries its source.