"Irrational exuberance" is back and stock market bulls are simply repeating the mistakes of the past, according to MarketWatch columnist Brett Arends.

Arends provided a cautionary list of reasons why he is getting "a horrible feeling of déjà vu . . . all over again" about stocks.

1. Valuations are way too rich. He notes the dividend yield today on the Standard & Poor's 500 has fallen to approximately 2 percent — about where it was during the 1996 peak.

Editor’s Note: 5 Reasons Stocks Will Collapse . . .

He pointed out stocks are trading at 24 times their per-share earnings of the previous 10 years — another measure of valuation — whereas the historical average is only 16 times earnings.

2. Too many bears are turning bullish. As an example, Arends mentioned two well-known bears, David Rosenberg of Gluskin Sheff and economist Nouriel Roubini, now believe the market is headed higher. When everyone is bullish, perhaps there is no one left to buy stocks, he suggested.

3. Nobody likes bonds. The fact that so many investors are avoiding bonds in favor of stocks should also be viewed as a warning sign, according to Arends.

4. The amount of leverage taken out by U.S. corporations may be another red flag.

"The plunge is interest rates that prevailed from 2009 through 2012 sparked a tsunami of new bonds as corporations rushed to borrow," Arends wrote in his MarketWatch column. According to Federal Reserve data, non-financial corporations have piled on more than $1 trillion in debt in the past three years, and their total liabilities have climbed to more than $14 trillion.

5. Individual investors are now heavily into stocks. The Investment Company Institute estimated reported net fund flows into mutual funds have been positive every month of 2013, totaling $108 billion in purchases.

"Let's remember that retail investors have, over time, proved to be absolutely terrible market timers," Arends noted.

"Those who bought stocks when the public was selling them, and sold them again when the public bought back in, have outperformed the overall market by a country mile for decades."

Recent gains mean U.S. stocks are having their best year in 2013 in a decade, helped by the belief the Fed will continue its ultra-loose monetary policies, Bloomberg noted.

U.S. equity values have grown by about $4 trillion.

Even more increases are likely because the economy is still expanding and past rallies survived higher interest rates, Brian Jacobsen of Wells Fargo Advantage Funds told Bloomberg.

"There's at least a firm foundation of fundamentals here, whereas during the tech bubble, that certainly wasn't the case," Jacobsen said. "During 2004 to 2006, the market still marched higher, and I don't see why it can't do that this time."

Editor’s Note: 5 Reasons Stocks Will Collapse . . .

Related Stories:

Jeremy Siegel: Dow Could Reach 17,000 By Year-End

CNBC: Signs Are Flashing of an Overbought Stock Market