Reading a Modified Dietz curve from original history
One fixed opening and successive closings show an approximate nonannualized return. Each point retains its original values, flows and any reason for a gap.
1. Choose an original opening and final closing
In Portfolio first explicitly apply unified history. Under Performance curve from this history select a Fixed opening day and later Final closing day. The curve includes at most 30 closing points within 31 calendar days including opening; every day must belong to the same original history.
Review curve and coverage shows the original opening value, each closing, coverage and unavailable reasons. Review does not yet calculate percentages. Only Calculate Modified Dietz curve creates the curve and every period result.
2. Every point starts on the same day
A point for a given closing means return from the same fixed opening through that closing. It is neither a standalone daily return nor a chain of daily percentages. It uses the unchanged method of Period return from this history, including original time weights for external contributions and withdrawals.
Modified Dietz is an approximate nonannualized return. It is not TWR, CAGR, a benchmark, tax or certified intraday calculation. A deposit itself is not return; value change remains distinct from return. Opening uses the original first day’s cutoff, so a flow already in opening value is not subtracted again.
3. Zero is a result, a gap is unavailability
The chart adds no assumed zero point at opening. An actually calculated zero is valid; a missing percentage remains a gap without interpolation. All daily closing points lists opening/closing values, net external contributions, weighted capital, percentage and the concrete reason. An unavailable point can be selected in the table.
Incomplete values, unsupported currency/flow, unsuitable weighted capital or an opening-basis correction can prevent return calculation. A known portion never substitutes for the complete endpoints required for return. A large journal may require fewer closing periods; the job has shared time and size bounds.
4. Open the exact period and all its flows
Select a point or closing day. This point’s period uses the same already-calculated period without recalculation. It shows return, value change, external contributions and weighted capital, then every original flow/classification: included, already in opening, after closing, reversed at closing or internal transfer. A flow exactly at closing has zero time weight.
Flow detail retains the original event, record, reversals and corrections for that closing. Original opening values and Original closing values open shared source detail for the exact day. Flow pagination does not exclude other flows from the period.
5. Whole file and current verification
Whole performance curve JSON or CSV contains every compact point, recipe, calculation identity, methodology and unchanged original history with sources once. Neither originals nor full flow rosters are copied thirty times. Selected point and flow page do not narrow the file.
Verify the same curve rechecks that history and current access without substituting newer prices. A changed draft is not automatically recalculated and the earlier curve does not belong to it. The curve uses currently recorded history and original reference prices; it proves neither a complete investment history nor prices known then. It creates no account save, financial Snapshot or share.
This is a guide to Datisto. Private features require sign-in and access to your own data. Personal models use your assumptions; availability and permitted use of source data are checked with the particular result. This is not investment advice.