Can the boom get boomier?

Do ultra-low interest rates justify ultra-high stock market values? Cormac Lucey shares his thoughts as US tech stocks continue their astonishing rise.

Are we experiencing a stock market bubble? The question arises because of the startling rebound in global stock market indices since last March and, in particular, because of the astonishing rise in value experienced by US tech companies. Since their March lows, the Nasdaq has nearly doubled, the NYSE FANG+ Index has risen by 150%, and Tesla has risen to an astounding 12.2 times its starting position. The other factor that suggests we are in the middle of an equity bubble is valuations.

The best measure of underlying long-term valuation is the Cyclically Adjusted Price Earnings (CAPE) ratio. It overcomes the weakness of the traditional Price Earnings (PE) ratio, that cyclically inflated earnings can make a cyclically inflated price look reasonable, by replacing one year’s earnings with average earnings over the previous 10 years, adjusted for inflation. The US CAPE is currently 35. That level has only ever been seen before as the Nasdaq bubble peaked in 2000. After that, the US tech index fell by three quarters before eventually bottoming in early 2002.

On one hand, Jeremy Grantham, founder of the GMO fund management group in Boston, reckons that US stock markets are in the final stages of a speculative bubble worthy of comparison with the dot-com bubble, the Great Crash of 1929, and the South Sea Bubble. On the other, Martin Wolf, a Financial Times columnist, doesn’t believe that we are currently experiencing a stock market bubble. He contends that equity prospects depend on the future course of corporate earnings and interest rates. He concludes that, provided the former are strong and the latter ultra-low, stock prices look reasonable. There’s the rub. Do ultra-low interest rates justify ultra-high stock market values? And how long will interest rates remain ultra-low?

On the face of it, the value of equity assets should rise as interest rates fall. Interest rates are a vital component of valuation models in general, and the Capital Asset Pricing Model in particular. When interest rates fall, the discount rate used in these models decreases and the price of the equity asset should appreciate, assuming all other things remain equal. Today’s interest rate cuts by central banks may therefore be used to justify higher equity prices and CAPE ratios. But John Hussman, a fund manager and former professor of finance, argues that when people say extreme stock market valuations are “justified” by interest rates, they’re actually saying that it’s “reasonable” for investors to price the stock market for long-term returns of nearly zero because bonds are also priced for long-term returns of nearly zero. “What’s actually happening today,” he argues, “is that investors are so uncomfortable with near-zero bond market valuations that they’ve priced nearly every other asset class at levels that can be expected to produce near-zero, or negative, 10-12 year returns as well.”

I agree with Hussman: US stocks are in a bubble. While equities may appear reasonably valued relative to bonds, in absolute terms their ultra-high valuations today suggest ultra-low investment returns over the coming 10-12 years for those who buy them now and hold onto them for several years. However, just because stocks are in a bubble doesn’t mean that they are about to fall. As the then-Taoiseach, Bertie Ahern, said in 2006: the boom can get boomier.

What should investors do? First, expect significant growth in short-term stock market volatility. The recent one-day 25% drop in the price of Bitcoin may be a straw in the wind. Second, the final market top may coincide with central banks allowing long-term interest rates to rise in the face of rising inflation expectations, perhaps in 2022. Until then, enjoy the boom getting boomier.

Cormac Lucey is an economic commentator and lecturer at Chartered Accountants Ireland.