Good news: Bubble concern is at a 5-year high
People are more interested in the concept of a "stock bubble" than they've been at any time since the housing bubble collapsed. But ironically, that very concern could be what prevents another bubble from forming anytime soon.
According to Google Trends, worldwide search interest in the term "stock bubble" is higher in November 2013 than in any month since October 2008. The rise in interest is even more pronounced in the United States, where in data going back to 2004, the volume of searches for the term is the highest it's ever been (with the exception of the bubble-period around November 2007.)
Paradoxically, many market participants say this should actually calm those who fret that equities are currently in a bubble.
"That means, conclusively, that there is no stock bubble," Jim Iuorio of TJM Institutional Services told CNBC.com. "It means that people aren't caught up in the hysteria of being deluded that there is no bubble, which is the only way that a bubble can exist."
Mark Dow, a former hedge fund manager who writes at the Behavioral Macro Blog, diagnoses investors with a bad case of "disaster myopia."
"If you went through an earthquake, or were mugged, or whatever traumatic event it might be, you overestimate the probability of that event occurring again," Dow said. "It's because we just went through a bubble that everyone's looking for them. Generals always fight the last war, and firemen fight the last fire."
Dow similarly believes that the tremendous deal of concern about a bubble will "probably prevent it," at least for a little while.
"It's never obvious, by definition, or you wouldn't get the bubble," he said.
(Read more: 3 technical reasons to be nervous about stocks)
That's not what Jesse Colombo sees. The economic analyst and Forbes contributor, who has amassed nearly 50,000 Twitter followers at the handle @TheBubbleBubble, successfully predicted the housing bubble, and currently sees another bubble growing in stocks.
"I'm very worried," Colombo told CNBC.com. "I predicted the last crisis, and I'm seeing the same things this time around that I predicted last time."
In the short term, Colombo is actually bullish, because "the bubble cycle can continue on for longer than many people would expect." But in the broader view, "It's typical bubble-driven growth, and it's being driven by rising margin debt."
(Read more: You're wrong—QE has not boosted stocks: McKinsey)
Dow dismisses the margin debt argument.
"That's just a function of interest rates being low," he said. "Guys can borrow at 1 percent, and they can buy munis that yield 4 or 5 percent double tax-free. Margin has more to do with the level of rates, and it's not an indication of frothiness or irrational exuberance."
In addition, Dow notes the ease with which one can predict a bubble.
"If you call a bubble, the kudos that you get can launch a career," Dow said. "If it doesn't work out, fine. But there's an optionality there. And everyone wants to be a hero."
All in all, Dow sees only one true bubble in the market.
"There's a bubble in calling for bubbles," he said.