Brian Feroldi Profile picture
Jul 24, 2023 15 tweets 5 min read Read on X
Peter Lynch LOVED the PEG ratio.

He popularized it in "One Up On Wall Street."

However, the PEG ratio actually SUCKS.

Here’s why: Image
Assume you’re considering investing in one of three companies.

Which is the better buy? Image
This is where the PEG ratio is useful.

PEG stands for “Price-to-Earnings-to-Growth”.

Divide the trailing P/E ratio by the estimated 5-year earnings growth rate.

The lower the number, the better.

The PEG makes it clear that Company ZYX is the best choice. Image
Peter Lynch used the following guidelines for judging the PEG ratio.

~0.5 = Undervalued ✅
~1.0 = Fairly Valued 🟡
~2.0 = Overvalued ❌ Image
Sounds great, right?

The PEG ratio certainly has some pros.

However, it also has a slew of cons: Image
Consider the "E" - Earnings

Here are 8 reasons why reported earnings might be misleading:

1: Accrual accounting
2: Equity investments
3: Windfalls
4: Unsustainable trend
5: Disruption
6: Cyclical demand
7: Industry Dynamics
8: Business growth cycle Image
Look at the PEG ratios for $AAPL, $MSFT, $GOOG, and $XOM from March 2023.

The PEG ratio made it seem like $XOM was a screaming buy: Image
But, the PEG ratio ignores that $XOM’s earnings are HIGHLY cyclical.

When energy prices are high, profits soar.

When they fall, profits tank.

That makes its “Earnings” - and hence its PEG ratio - unreliable. Image
The PEG ratio only works when a company is:

1) Growing
2) Optimized for normalized earnings

That’s a sweet spot that only exists between phases 4 & 5 of the business growth cycle.

That makes the PEG ratio useless when a business is in phases 1, 2, 3, or 6 Image
The growth rate is also troublesome.

What if the estimated 5-year growth rate is wrong? The PEG ratio will mislead you.

Analyst estimates tend to be overly optimistic (and are later revised downward) Image
To fix these issues, some investors use variations on the PEG ratio.

Here are some standard adjustments: Image
All valuation metrics have flaws.

What should investors do?

Learn to use a variety of valuation metrics and know when they are USEFUL and when they are USELESS.

Use this chart as a guide: Image
If you invest, you MUST understand valuation.

Want help?

Join me in August for my cohort-based course - Valuation Explained Simply

Interested? DM me for a coupon code.

https://t.co/1Qte591VZBmaven.com/brian-feroldi/…
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More from @BrianFeroldi

Sep 6, 2025
Tangible vs Intangible Assets.

What's the difference?

Here's everything you need to know: Image
They confused me until I discovered an easy way to distinguish them:

𝗧𝗮𝗻𝗴𝗶𝗯𝗹𝗲 𝗔𝘀𝘀𝗲𝘁𝘀 𝗖𝗮𝗻 𝗕𝗲 𝗧𝗼𝘂𝗰𝗵𝗲𝗱

𝗜𝗻𝘁𝗮𝗻𝗴𝗶𝗯𝗹𝗲 𝗔𝘀𝘀𝗲𝘁𝘀 𝗖𝗮𝗻'𝘁 Image
Another major difference.

- Tangible assets are depreciated

- Intangible assets are amortized Image
Read 6 tweets
Aug 31, 2025
How to analyze an Income Statement, FAST.

Warren Buffett’s 8 Income Statement 'Rules of Thumb': Image
1: Gross Margin

🧮 Equation: Gross Profit / Revenue

👍 Rule of Thumb: 40% or higher

🤔 Buffett's Logic: A consistently high gross margin signals that the company isn’t competing exclusively on price. Image
2: SG&A Margin

🧮 Equation: SG&A Expense / Gross Profit

👍 Rule of Thumb: 30% or lower

🤔 Buffett's Logic: Wide-moat companies don’t need to spend a lot on overhead to operate & convince consumers to buy. Image
Read 11 tweets
Aug 30, 2025
Some stocks are STRONG BUYS when they fall

Other stocks are SELLS when they fall

How can you tell the difference?

Watch for these 5 financial yellow flags: Image
1) GOODWILL WRITEDOWN

This represents the premium a company pays for an acquisition above its fair market value.

If there’s a major goodwill write-down on the Income Statement, it means management has wasted a TON of capital. Image
2) GROSS MARGIN DECLINING

1: The competition is forcing me to lower prices
2: Demand is weak
3: My suppliers are raising prices

Either way, it can be a thesis-busting development Image
Read 9 tweets
Aug 29, 2025
Capitalism is brutal.

If you invest, you MUST know how to identify a moat.

Here are 9 financial “rules of thumb” that Warren Buffett uses to tell if a company has one: Image
1: Gross Margin

Found: Income Statement

Formula: Gross Profit / Revenue

Moat: Consistently above 40%

No Moat: Under 40% & volatile Image
Buffett’s logic:

A consistently high gross margin signals that the company isn’t competing exclusively on price.

A high gross margin also provides ample gross profit to pay expenses and leaves money for shareholders.
Read 22 tweets
Aug 27, 2025
How to analyze an income statement in less than 2 minutes: Image
The income sheet is one of the three major financial statements.

It shows a company’s:
▪️Revenue (Sales)
▪️Expenditures (Costs / Expenses)
▪️Net Income (Earnings, Profits)

Over a period of time. Image
Management teams have leeway in categorizing their income statement.

This means that not all income statements look the same.

Here is a typical layout and the meaning of the most commonly used terms: Image
Read 11 tweets
Aug 26, 2025
Financial Statements For Beginners

Want to learn accounting?

Study these 9 simple infographics (a visual thread) ↓ Image
Image
Financial Statements DO NOT have a universal layout

Here are some other balance sheet terms you might see: Image
Read 9 tweets

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