2 Important Ratios You Should Look at Before Buying Any Stock

Canadian National Railway (TSX:CNR)(NYSE:CNI) is a great example of a stock that trades at very modest multiples and that could be a solid investment to make today.

| More on:

Valuations for a stock can get out of control sometimes. However, over the long term, investors can expect to see things stabilize and return to more normal levels.

A good example of this is the cannabis industry, where valuations have often become obscene, with promises of future growth being enough for many investors to forgive many other shortcomings, including poor market share and little hope for profitability in the imminent future.

It’s not surprising that we’ve seen some of those highly priced stocks fall in value recently. Investors can, however, protect themselves from big corrections in share price by simply taking a look at a couple of important ratios that will quickly help identify if there is a problem with a stock’s value.

Price-to-earnings ratio

The first ratio is a very common one, price-to-earnings (P/E). It’s an easy one to calculate and serves as a very good benchmark when comparing other companies.

It is calculated by taking the current stock price and dividing it by the earnings per share (EPS) that the company has generated over the past four quarters.

As it involves price, it has the opportunity to fluctuate very quickly, but can help you make a quick assessment of whether a stock is overpriced or not.

Let’s look at Canadian National Railway (TSX:CNR)(NYSE:CNI) as an example. Over the past four quarters, the company has generated profits of $4.4 billion.

If we divide that by 725 million shares, that gives us an EPS of a little over $6.1. With the stock price around $124, its P/E is a little more than 20.

Value investors might sometimes target a P/E that’s 15 or less, although 20 isn’t a very high multiple, especially since CN Rail has shown some good growth over the years.

Generally, a P/E of 15 or less is most suitable for stocks that don’t have a lot of growth. Tech stocks may often trade at 30 times their earnings, or even higher.

But if you see a stock that’s trading more than 100 times its earnings, it’s something that warrants further investigation. It could be that the company has had a bad quarter dragging down its numbers over the past year, or it could be a sign that the stock has simply gotten too expensive.

If a company doesn’t have any earnings, then obviously a P/E ratio won’t be very helpful. This is where we can move on to the next multiple:

Price-to-sales multiple

Using a price-to-sales (P/S) multiple is another valuable tool in assessing value. This calculation involves taking the company’s market cap and dividing it by its sales over the past year.

If we go back to CN Rail, the stock has a value of around $89 billion. And over the past four quarters, sales have totaled $15 billion. This tells us that CN Rail’s P/S ratio is at around 5.9.

There’s a lot more variability here as to what’s acceptable, but generally, if you’re under a P/S of 10 then that’s good. Ideally, however, you’d like to see the multiple as low as possible.

Here again, it would’ve helped flag high-flying cannabis stocks that were trading more than 100 times their sales.

Bottom line

These multiples can help you get an idea of how much of a premium you’d be paying to own a stock today. It’s also helpful when comparing similar investments.

Ultimately, there are many other ways you can assess a company’s value, but these two ratios can, at a minimum, help you identify stocks which are grossly overvalued based on their recent performances.

Fool contributor David Jagielski has no position in any of the stocks mentioned. CN is a recommendation of Stock Advisor Canada.

More on Dividend Stocks

Piggy bank on a flying rocket
Stocks for Beginners

Where to Invest Your $7,000 TFSA Contribution for Long-Term Gains

Looking for where to allocate your TFSA contribution? Here are two options to direct that $7,000 where it will give…

Read more »

The virtual button with the letters AI in a circle hovering above a keyboard, about to be clicked by a cursor.
Dividend Stocks

1 Canadian Stock Ready to Surge in 2026 and Beyond

Open Text is a Canadian tech stock that is down 40% from all-time highs and offers a dividend yield of…

Read more »

A plant grows from coins.
Dividend Stocks

3 Reasons I’ll Never Sell This Cash-Gushing Dividend Giant

Here's why this dividend stock is one of the most reliable companies in Canada, and a stock you can hold…

Read more »

Real estate investment concept with person pointing on growth graph and coin stacking to get profit from property
Dividend Stocks

Invest $30,000 in 2 TSX Stocks and Create $1,937 in Dividend Income

These TSX stocks have high yields and sustainable payouts, and can help you generate a dividend income of $1,937 annually.

Read more »

A meter measures energy use.
Dividend Stocks

What to Know About Canadian Utility Stocks in 2026

Here's how much potential Canadian utility stocks have in 2026, and whether they're the right investments to help shore up…

Read more »

A close up color image of a small green plant sprouting out of a pile of Canadian dollar coins "loonies."
Dividend Stocks

1 Incredibly Cheap Canadian Dividend-Growth Stock to Buy Now and Hold for Decades

With this top dividend-growth stock trading 40% off its 52-week high, and offering a yield of 4.4%, it's easily one…

Read more »

Retirees sip their morning coffee outside.
Dividend Stocks

Here’s How Much a 40-Year-Old Canadian Needs Now to Retire at 65

If you invest in iShares S&P/TSX 60 Index Fund (TSX:XIU), you'll likely be able to retire at 65.

Read more »

dividend stocks are a good way to earn passive income
Dividend Stocks

Top TSX Income Stocks to Start Your 2026

If you are looking for income-producing stocks on the TSX, here are four growing dividend stocks to buy.

Read more »