Note · Opinion, not rated
A growth rate is a flow divided by a stock.
Recurring revenue, subscribers, a loan book, a backlog: every one is a stock fed by a flow. The growth rate everyone quotes belongs to the stock. The one that tells you what happens next belongs to the flow, and it can collapse while the headline barely moves.
The arithmetic
A stock is an amount at a point in time: subscribers today, annual recurring revenue today, loans on the books today. A flow is the change over a period: net subscribers added, net new recurring revenue, net new loans. The stock's growth rate is the flow divided by the stock it was added to. Nothing more.
That definition has a consequence people rarely think through. The year-over-year growth rate of a stock is the sum of four quarters of flow, divided by the stock a year ago. So when the flow changes, only a quarter of the change shows up in the next reported number. The headline is a trailing average of the thing that matters, and it lags it by up to a year.
What a 36.5% fall in the flow does to the headline
Take a stock of 100 growing 11.2% a year in steady state, with its flow growing at the same rate. Then let one quarter's net additions come in 36.5% below the same quarter a year earlier. Three things could happen next. The weak quarter is a one-off and the flow returns to trend. Or the flow resets lower for a full year and then resumes growing. Or it resets lower and simply stays there.
| Reported growth of the stock | No shock | One-off | Resets for a year | Resets and stays flat |
|---|---|---|---|---|
| Quarter 1 | 11.20% | 9.95% | 9.95% | 9.95% |
| Quarter 2 | 11.20% | 9.98% | 8.73% | 8.69% |
| Quarter 3 | 11.20% | 10.02% | 7.55% | 7.42% |
| Quarter 4 | 11.20% | 10.05% | 6.40% | 6.14% |
| Quarter 5 | 11.20% | 11.33% | 6.47% | 6.05% |
| Quarter 8 | 11.20% | 11.32% | 6.68% | 5.79% |
Read the first row. A fall of more than a third in the thing that feeds the stock moves the headline growth rate from 11.20% to 9.95%. That is 1.25 points. And it moves it by exactly the same amount in all three cases, so on the day it is reported, the headline cannot tell you which world you are in.
By the fourth quarter it can. The one-off case is still sitting at 10.05%, because the weak quarter stays inside the trailing year for exactly four quarters, and it snaps back to 11.33% the moment it drops out. The other two are at 6.40% and 6.14%, a little over half where they started. Anyone watching only the headline learned that three quarters after the flow could have told them.
The stock tells you about last year. The flow tells you about next year.
A flat flow is not a steady business
The second consequence is less obvious and more important. Suppose nothing breaks at all. The flow simply stops growing and adds the same amount every year, forever. That sounds like a stable business. Here is what it does to the growth rate.
| Flow stops growing | Stock growth that year |
|---|---|
| Year 1 | 10.1% |
| Year 2 | 9.2% |
| Year 3 | 8.4% |
| Year 5 | 7.2% |
| Year 7 | 6.3% |
| Year 9 | 5.6% |
| Year 10 | 5.3% |
Growth falls to half its starting 11.2% by year 9, with nothing having gone wrong anywhere. The stock keeps getting bigger and the same absolute addition is a smaller and smaller share of it. A company whose net additions are merely flat is, arithmetically, a company whose growth rate is decelerating every year. And in the long run, as long as the flow keeps growing, the stock's growth rate ends up wherever the flow's growth rate is.
| If the flow grows | Stock growth after forty years |
|---|---|
| +11.2% a year | +11.2% |
| +5.0% a year | +5.4% |
| 0.0% a year | +2.0% |
| -5.0% a year | +0.5% |
With a growing flow, the stock converges to the flow's rate. With a flat or shrinking flow that is still positive, the stock's growth rate decays toward zero but stays above it: the stock only starts shrinking once net additions themselves turn negative. The draft of this note said a shrinking flow eventually shrinks the stock. The model said otherwise, and the model was right.
Where this came from
We were reminded of all this writing our report on Adobe. Adobe's total annual recurring revenue reached $27.5 billion at the end of its fiscal third quarter and grew 11.2% year over year. That is the stock. On the earnings call an analyst put it to management that net new recurring revenue, the flow, was down 36 to 37 percent on the same quarter a year earlier. Management did not dispute the figure and attributed the decline to its freemium strategy and to seasonality.
We are not claiming Adobe is in the right-hand column of the table above. One weak quarter is not a weak year: management guided full-year ending ARR growth of 10.2% and described the fourth quarter as seasonally strong. What the arithmetic does say is which number to watch. If the flow recovers in the fourth quarter, this was the one-off column and the headline barely notices. If it does not, the headline will drift toward the reset column over the following year, and the reported growth rate will be the last place that shows it.
Where else it applies
Subscribers. Net adds are the flow. A streaming service or a software company reporting a large subscriber base growing at a respectable rate on shrinking net adds is reporting the past.
Banks. Loans outstanding and deposits are stocks; originations and net deposit flows are the flows. A loan book can show steady growth for a year after new lending has slowed.
Backlog. Remaining performance obligations are a stock; the flow is new bookings less the revenue recognized out of it. Adobe's backlog grew 8% while revenue grew 13%, and the current portion, the contracted revenue due over the next twelve months, grew 9%. The backlog is still being added to, just more slowly than revenue is growing, and over time revenue growth tends toward the growth of the backlog it is drawn from.
You. Your net worth is a stock and saving is a flow, along with whatever your investments earn. Early on, the flow is everything. Later, the stock takes over.
| Saving $20,000 a year at 5% | Net worth | Share of that year's growth that was saving |
|---|---|---|
| Year 1 | $20,000 | 100% |
| Year 5 | $110,513 | 82% |
| Year 10 | $251,558 | 64% |
| Year 20 | $661,319 | 40% |
| Year 30 | $1,328,777 | 24% |
Which is the arithmetic behind your savings rate is the whole game in the first decade, and behind coast FIRE in the third.
What to read instead
Find the flow and read it directly, both against the prior quarter and against the same quarter a year ago. Net adds, net new recurring revenue, originations, bookings. It is usually disclosed somewhere, if not in the headline.
Treat a growth rate that is holding up while the flow falls as a lagging indicator, not as reassurance. It is a trailing average doing exactly what trailing averages do.
And notice when a company stops disclosing the flow. Companies publish the number that flatters them. A switch from reporting net adds to reporting only the total is information, and it is rarely good news.
Sources
- Adobe third quarter fiscal 2026 earnings release, exhibit 99.1 to the Form 8-K filed September 10, 2026, for total ARR, its growth rate, and the full-year ARR guidance.
- Adobe third quarter fiscal 2026 earnings call transcript, September 10, 2026, for the net new ARR exchange and management's attribution of it. The decline is an analyst's figure that management did not dispute, not a company disclosure.