Anybody who’s done any trading or investing is familiar with the standard financial HLOC time-series chart. Even Excel has ‘em. You take an underlying time-series of price data (sometimes recording in sub-second time-frames) and you just bin those raw numbers. The “1-minute” HLOC stock chart, for example, shows you the high, low, open and close prices aggregated over every discrete 1-minute period. The “30-minute” HLOC chart divides the same underlying data into 30-minute blocks. Same data, different views. These are daily workhorses for anybody who deals with equity prices.

What I want is the same functionality for my portfolio’s total value. Multiply each price tick by my holding of that security, combine them into a single time-series, and add them up over time.

You’d think that would be obvious. Not so! I can’t find a single online vendor—Google Finance included—who can do the simple arithmetic. Actually, they do the arithmetic, because there’s always a line-item on the values table showing total portfolio value. But they never chart it.

How hard is it to make that mental leap, people? Graph it. Show, don’t tell.