djiaU.S. markets are at new all-time highs. Talking heads are calling for Dow 20,000… even 21,000.

Euphoria has swept the Street.

The US dollar is rocketing.

But wait, there’s more…

—by Ian L. Cooper

The good news just can’t come out fast enough:

Companies have announced they’ll bring jobs back to the US…

Bank stocks are running on speculation surrounding lax regulations…

The Dow, the S&P 500, the NASDAQ are all in record territory…

But it can’t last.

There’s no logic, no fundamental reason for it too. The cyclically adjusted P/E (CAPE) – a valuation metric created by Robert Shiller – now sits at 27.90.

The last time it was this high was Black Monday 1929.

In 2008, it hit 27. In 2000, it hit highs of nearly 45. And we know all too well how that turned out.

History clearly reminds us there is no logical way stocks can remain at these elevated levels. However, traders don’t want to hear that. We have to remember that after the Dow ran nearly 330% higher from October 1923 to the crash of October 1929, a great deal of it was mired in heavy speculation and borrowed money.

We’re seeing that again now.

Also during the 1920s, the Dow hit 27 highs in eight years. Even now, after nearly eight years and 28 record highs, we’re running into the same issue: There’s no support. Also, in 1929, a great deal of investors piled billions into the markets. Share prices kept soaring, creating this artificial, unsustainable rally.

Today, markets are fueled by the same speculative behavior, creating another unsustainable bubble. After looking at this chart, does it look sustainable to you?