Markets are arguably expensive by history, but this environment of accelerating not only earnings but also economic strength is what’s catching the market’s attention right now.

At a first glance, the US markets look expensive because the S&P500 is currently trading on a Price-to-Earnings Ratio of 23 times. The only time the markets looked more expensive by using the same metric was before the dot.com bubble in the late 90s when the Price-to-earnings multiple was at 29.5 times.

What is the Price-to-earnings Ratio?

The price-earnings ratio (P/E ratio) is the ratio for valuing a company that measures its current share price relative to its per-share earnings. The price-earnings ratio is also sometimes known as the price multiple or the earnings multiple.

So why does the US market continue to rally?

The Price-to-Earnings ratio is using historical earnings. Analysts are forecasting that per-share profit in the S&P 500 will rise 15 percent in 2018, the fastest rate since 2011. They expect growth to approach 13 percent a year through 2023.

Incorporating the above forecasts, stocks look as though they are getting cheaper. Even with the S&P 500 sitting 47 percent above its February 2016 low.

While the current 1.43 PEG ratio still exceeds the average of 1.24 since 1985, it’s down from a record 1.72 in early 2016 and trails readings during four distinctive periods.

What is the PEG Ratio?

The price/earnings to growth ratio (PEG ratio) is a stock's price-to-earnings (P/E) ratio divided by the growth rate of its earnings for a specified time period. The PEG ratio is used to determine a stock's value while taking the company's earnings growth into account, and is considered to provide a more complete picture than the P/E ratio.

Conclusion

The data may be one reason why stocks continued to rally, defying forecasts that elevated valuations means muted returns. The S&P 500 has risen every day this year, building on the best annual gain since 2013 amid expectation that a pickup in profit growth will help alleviate pressure from stock multiples.