To master the comparison game, you must first understand the tools of the trade. In relative valuation, these tools are "multiples." While there are dozens of possible ratios, three stand out as the gold standards used by professional analysts: Price-to-Earnings (P/E), Enterprise Value to EBITDA (EV/EBITDA), and Price-to-Book (P/B).

Equity Multiples vs. Enterprise Value Multiples

Before diving into the specific ratios, we must distinguish between two categories: Equity Multiples and Enterprise Value (EV) Multiples .

Equity Multiples: These ratios look at the value of the company's shares (equity) relative to a metric that belongs to the shareholders (like Net Income). The most famous example is the P/E ratio .
Enterprise Value Multiples: These ratios look at the value of the entire business (both debt and equity) relative to a metric that is available to all capital providers (like EBITDA or Sales) .

Analysts often prefer Enterprise Value multiples because they allow for a direct comparison of firms regardless of their capital structure (how much debt vs. equity they use) . Equity multiples can be "artificially impacted" by a change in debt, even if the actual business hasn't changed .

1. Price-to-Earnings (P/E): The Investor's Favorite

The P/E ratio is the most widely recognized valuation metric in the world. It measures how much investors are willing to pay for every $1 of a company's earnings .

The Formula:
$$P/E Ratio = \frac{\text{Market Price per Share}}{\text{Earnings Per Share (EPS)}}$$

There are two main types of P/E ratios:

Trailing P/E: Uses earnings from the past 12 months. It is based on "hard data" but is backward-looking .
Forward P/E: Uses estimated earnings for the next 12 months. This is more consistent with valuation principles—that a company is worth the present value of future cash—but it relies on analyst guesses .

Example:
If Bank of America is trading at $40 per share and its EPS is $3.00, its P/E ratio is 13.33x ($40 / $3). This means investors are paying $13.33 for every $1 of profit the bank generates .

When to use it: P/E is best for established companies with consistent, positive earnings. It is less useful for startups or companies in cyclical industries where earnings fluctuate wildly .

2. EV/EBITDA: The Professional's Choice

While P/E is popular, professional analysts often lean on the Enterprise Multiple (EV/EBITDA). This ratio relates the total value of a company from all sources (Enterprise Value) to its operating cash earnings (EBITDA) .

Understanding Enterprise Value (EV)

To use this multiple, you must first calculate Enterprise Value. EV is a more comprehensive measure than market capitalization because it accounts for a company's debt and cash reserves .

The Formula for EV:
$$EV = \text{Market Cap} + \text{Total Debt} - \text{Cash and Cash Equivalents}$$

Market Cap: The total value of all outstanding shares .
Total Debt: Both short-term and long-term debt. An acquirer would have to "settle" these debts if they bought the company .
Cash: Subtracted because an acquirer could use the company's own cash to pay off part of the purchase price .

Understanding EBITDA

EBITDA stands for Earnings Before Interest, Taxes, Depreciation, and Amortization. It is used as a proxy for a company's ability to generate cash from its core operations, stripping out the effects of financing (interest) and government policy (taxes) .

The Formula for EV/EBITDA:
$$\text{Enterprise Multiple} = \frac{EV}{EBITDA}$$

Why it’s powerful: It is ideal for comparing companies with different levels of debt. It is also great for capital-intensive industries (like oil and gas or manufacturing) where high depreciation expenses can make "Net Income" look artificially low .

3. Price-to-Book (P/B): The Reality Check

The P/B ratio compares a company's market value to its "book value"—the value of all its assets minus its liabilities . Essentially, it tells you what the company is worth on paper according to its balance sheet.

The Formula:
$$P/B Ratio = \frac{\text{Market Price per Share}}{\text{Book Value per Share (BVPS)}}$$

What it tells you:

P/B < 1.0: The stock is trading for less than the value of its net assets. This is often a signal for "value investors" that a stock is undervalued .
P/B > 1.0: The market is paying a premium for the company’s brand, intellectual property, or future growth potential .

When to use it: P/B is the "gold standard" for valuing banks and financial institutions, where assets (loans) and liabilities (deposits) are the core of the business . It is less useful for service or tech companies (like Microsoft or Google) because their most valuable assets—their code and people—don't show up on the balance sheet as "tangible assets" .

Summary Table: Which Multiple Should You Use?

Industry	Preferred Multiple	Why?
Banking / Finance	Price-to-Book (P/B)	Assets and liabilities are the core of the business .
Manufacturing / Telecom	EV/EBITDA	Accounts for high debt and heavy equipment depreciation .
Retail / Consumer Goods	Price-to-Earnings (P/E)	Focuses on the bottom-line profit available to shareholders .
Early-Stage Tech / SaaS	EV/Sales	Used when the company isn't profitable yet .
Real Estate (REITs)	Price-to-Cash Flow	Cash flow is more important than accounting profit .

The "Explain Like I'm 5" Sidebar: The Car Analogy

Imagine you are buying a used car.

P/E Ratio is like looking at the car's gas mileage. You want to know how much "distance" (profit) you get for every dollar you spend on the car.
EV/EBITDA is like looking at the total cost of the car including the loan you have to take over, minus the spare change found in the glove box. It gives you the "true" price of the whole machine.
Price-to-Book is like looking at the value of the car's parts if you were to take it to a scrap yard. It’s the "safety net" value of the physical stuff the car is made of.

By using these ratios in tandem, analysts can build a comprehensive picture of a company's value. However, a ratio is only useful if you have something to compare it to. In the next section, we will learn how to select the "Comparable Group" that makes these numbers meaningful.