Imagine a fund that earned exactly zero for a month. Nothing made, nothing lost.
That same month, three investors deposited. The balance chart climbed 67%.
The performance was still zero.
This is why balance is one of the most misleading numbers in finance - not because it's wrong, but because it answers a question you never actually asked.
Two different questions
Balance answers: how much is currently in this account?
That number moves for two completely different reasons. It moves because the fund made or lost money - that's performance. And it moves because you put money in or took money out - that's just plumbing. A deposit makes your balance jump. Nothing about the fund changed. Your balance is simply larger because you added to it.
NAV per unit answers a different and better question: how good is this fund, per dollar, regardless of how much is in it?
It's the same idea as a share price. A company's total market cap goes up when it issues new shares - but the share price only moves on the business. NAV per unit is our share price.
How it's built
The pool holds assets - cash plus the live, marked value of every open position. Divide that by the number of units outstanding and you get the price of one unit.
When you invest, you don't "add to a balance." You buy units at the current NAV per unit. From then on you own a fixed number of units, and your value is just your units times the current unit price.
This is why the mechanism matters. When someone deposits, we mint new units and add their cash in the same step. Units up, NAV up, by exactly the right amounts. NAV per unit doesn't budge. Their deposit cannot lift - or dilute - your unit price. Performance and plumbing are finally separated.
Watch what happens in practice
Suppose the fund's unit price is flat for a month - genuinely flat, zero performance - but three investors deposit. Track the two numbers:
Now run it the other way. The fund has a great month, up 4%, but you withdrew to pay a tax bill. Your balance fell. Your NAV per unit rose. Balance told you a story that was the exact opposite of the truth.
Balance tells you how much you have. NAV per unit tells you whether the fund deserves it. Only one of those is a measure of performance.
This is also why some investment products would rather show you a balance than a NAV per unit. A balance is easy to inflate with inflows - more deposits, bigger number. A NAV per unit is not. It only moves on the work.
What to actually watch
- Judging the fund? Watch NAV per unit, and the drawdown of NAV per unit. That's performance, clean of your own deposits and withdrawals.
- Checking your slice? Multiply your units × NAV per unit. That's your value, and it reconciles to the ledger to the rounding error.
- Reconciling a statement? Your deposits and withdrawals explain the gap between "units × price" and "what I remember putting in." That gap is plumbing, not performance.
None of this is exotic. Every serious fund in the world runs on units and NAV - it's just usually hidden behind a balance figure, because balance is the number that's easiest to make look good. We put NAV per unit on the surface on purpose.
If you remember only one thing from this piece, remember this:
Balance tells you how much money is in the account.
NAV tells you whether the account is actually doing its job.