What it means
Earnings growth is not the same as revenue growth. A company's operating leverage, the mix of fixed and variable costs in its business, can make earnings grow faster or slower than revenue, and earnings growth itself can come from margin expansion, from revenue growth, from share buybacks that reduce the share count without any change in net income, or from some combination of all three.
Understanding which of these is driving a reported growth figure matters more than the headline number alone. A single year's growth rate compares this period's earnings with the prior period's.
A compound annual growth rate, or CAGR, instead measures the average annual rate of growth over several years, smoothing out the volatility that a single-year figure can show. Because individual years can be lifted or depressed by one-off items, analysts generally prefer a multi-year CAGR when judging a company's underlying trend, reserving single-year figures for explaining what happened most recently.
Earnings per share growth and net income growth can diverge sharply because of share buybacks. A company can grow EPS faster than net income simply by shrinking its share count, which is real value creation for the shareholders who remain, but it is not the same as the underlying business growing faster, and an investor who does not separate the two can overstate how much operating momentum a company actually has.
The quality of a growth figure matters as much as its size. Growth achieved through acquisitions can inflate a group's consolidated earnings without any organic improvement in the underlying businesses.
A very high growth rate in a single year is often a base effect: the prior year's earnings were unusually low because of a one-off charge, and the following year's percentage increase looks dramatic mainly because the starting point was depressed, not because the business suddenly accelerated. How the market prices growth is captured by the PEG ratio, a company's price-to-earnings ratio divided by its earnings growth rate, which normalises a valuation multiple for how fast the company is growing.
Sustained high growth rates are rare and tend to slow as a company matures or faces ever-larger comparison bases, so extrapolating a high historical growth rate far into the future, without allowing for that natural slowdown, is one of the most common mistakes in equity valuation.
In practice
Real-world examples.
Example
A retailer's net income grows 8% for the year, but EPS grows 14% because a large share buyback reduced the share count by about 5%, and analysts note that underlying business growth was more modest than the EPS headline suggests.
Example
A company's reported earnings growth of 85% in one year turns out to be a base effect: the prior year's earnings had been depressed by a one-off legal settlement, and normalised growth once that is excluded is closer to 12%.
Example
An investor uses the PEG ratio to compare two companies both trading at a price-to-earnings ratio of 30: one growing earnings at 30% a year, a PEG of 1.0, and one growing at 10%, a PEG of 3.0, and concludes the first is more reasonably priced relative to its growth despite the identical headline multiple.
Think of it
“Earnings growth is like tracking how much more money you actually pocket from your business after all expenses.
Formula
Calculation
Single-period earnings growth = (Current period earnings minus Prior period earnings) / Prior period earnings x 100
Compound Annual Growth Rate (CAGR) = (Ending earnings / Beginning earnings) to the power of (1 / number of years) minus 1
EPS growth = (Current EPS minus Prior EPS) / Prior EPS x 100
PEG ratio = Price-to-Earnings ratio / Earnings growth rate (expressed as a whole number, so 15% growth is entered as 15)
Worked example. A company's net income was $10,000,000 in Year 1, $11,500,000 in Year 2, $13,800,000 in Year 3, and $15,180,000 in Year 4.
Year 2 growth = (11,500,000 minus 10,000,000) / 10,000,000 = 15%
Year 3 growth = (13,800,000 minus 11,500,000) / 11,500,000 = 20%
Year 4 growth = (15,180,000 minus 13,800,000) / 13,800,000 = 10%
Three-year CAGR from Year 1 to Year 4 = (15,180,000 / 10,000,000) to the power of (1/3), minus 1 = approximately 14.9%, smoothing the 15%, 20% and 10% annual figures into a single representative trend.
Share buyback effect. In Year 1, the company had 10,000,000 shares outstanding, giving EPS of 10,000,000 / 10,000,000, or $1.00. By Year 4, buybacks had reduced the share count to 8,000,000, so EPS = 15,180,000 / 8,000,000 = $1.90.
Net income growth over the period = (15,180,000 minus 10,000,000) / 10,000,000 = 51.8%
EPS growth over the same period = (1.90 minus 1.00) / 1.00 = 89.8%
Buybacks contributed roughly 38 percentage points of the EPS growth beyond what the underlying net income growth alone would explain.
PEG example. The company trades at a price-to-earnings ratio of 22.5, with expected earnings growth of 15% a year: PEG = 22.5 / 15 = 1.5, which many investors would read as moderately, but not extremely, expensive relative to its growth.Case study
Seen in the real world.
An analyst covering a mid-cap software company was initially excited by a headline figure showing earnings growth of 140% in the most recent fiscal year, net income rising from $4,000,000 to $9,600,000. A colleague asked what had happened to the prior year's earnings to make the base so low.
The prior year's net income of $4,000,000 had been depressed by a one-off litigation charge of $3,500,000; without it, normalised prior-year earnings would have been closer to $7,500,000. Recalculated on that basis, growth was (9,600,000 minus 7,500,000) / 7,500,000, or 28%, a very different, and far more representative, figure than the headline 140%.
To get a still more reliable read, the analyst pulled a longer run of figures: net income of $6,800,000 two years before the litigation charge, $4,000,000 in the depressed year, $9,600,000 the following year, and $10,800,000 in the most recent year. A three-year compound annual growth rate from the pre-charge base to the latest year, (10,800,000 / 6,800,000) to the power of (1/3) minus 1, worked out to approximately 16.7%, bridging cleanly across the anomalous year and giving a trend the analyst was comfortable using in a valuation.
Applied to the stock's price-to-earnings ratio of 34, the misleading headline growth rate would have produced a PEG of 34 / 140, or 0.24, suggesting the stock was extremely cheap relative to its growth. Using the 16.7% CAGR instead, the PEG came to 34 / 16.7, approximately 2.0, a materially richer valuation picture. The analyst's note to the investment committee concluded that the stock was fairly, rather than cheaply, valued, and that the 140% headline figure should never have been used in a valuation without first checking what had happened in the base year.
Watch out
Common mistakes.
- Comparing a single year's earnings growth to a depressed or unusually high prior-year base without checking what drove that base year, producing a growth percentage that is technically correct but practically meaningless.
- Treating EPS growth and net income growth as interchangeable, when share buybacks can make EPS grow substantially faster than the underlying business.
- Extrapolating a high historical growth rate far into the future without considering that high growth rates are difficult to sustain and tend to slow as a company matures or faces larger comparison bases.
Questions
People also ask.
What is a good earnings growth rate?
It depends heavily on the company's size, industry and stage. A large, mature company growing earnings at 5 to 8% a year may be performing well, while investors often expect 15% or more from a smaller, faster-growing company, and what matters most is whether the rate is sustainable and of good quality.
Why use a multi-year CAGR instead of the most recent year's growth rate?
A single year's growth rate can be distorted by one-off items or an unusual prior-year base, while a compound annual growth rate over several years smooths out that volatility and gives a more representative picture of the underlying trend.
How does the PEG ratio use earnings growth?
It divides a company's price-to-earnings ratio by its earnings growth rate, producing a single figure that adjusts a simple valuation multiple for how fast the company is growing, so that a high P/E supported by high growth can be compared fairly with a lower P/E supported by slower growth.
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