Cramer: Has nobody noticed elephant in market?

Looking inside the market, CNBC's Jim Cramer sees a potential problem. And it could be a big one.

It has nothing to do with the Ukraine, the Middle East, China or Ebola. "That's what everyone else is worrying about," Cramer said. "I don't like to worry about what everyone else is worrying about."

Cramer says those negatives are already known; and no matter how bad they may be, they don't pose the threat of a nasty surprise.

Elephant in room
Matthias Clamer | Getty Images

However, something else does. And Cramer says nobody is talking about it, yet it could, potentially, take down your portfolio, substantially.

What's the issue? "It's the newfound supply," Cramer said, "and it's got me nervous."

That is, Cramer is again seeing a glut of new offerings coming onto the market, with the Alibaba IPO potentially the biggest.

The problem, Cramer says, is that there isn't enough new money coming into the market to match the quantity of new stock coming onto the market.

"That's one of the oddities of this amazing bull market," he noted. "It doesn't draw in new dollars. It just kind of putters along without any real fuel other than corporate buybacks and mergers and acquisitions."

Therefore, Cramer believes as its IPO draws near, mutual fund managers who want or need exposure to Alibaba will have to sell other holdings.

"So I expect they will sell Apple and Google, Facebook and other winners to fund their Alibaba purchases," Cramer speculated.

Read more from Mad Money with Jim Cramer
Europe compromising health of U.S.?
Football lovers good stock pickers!
Deckers on brink of revolution

Of course, if the phenomenon were limited to Alibaba, Cramer would be far less concerned. But he doesn't think that's the case.

"No, it's what's after Alibaba that has me worried," Cramer said. That is, there are a string of other IPOs coming that Cramer believes fund managers will also either want or need to buy including AirBNB, DropBox, Box and Uber.

"Mutual funds might have to come up with as much as $75 billion, maybe even more. That's $75 billion that these funds just don't have lying around," Cramer said.

Therefore, Cramer thinks these money managers will have to sell winners to fund their new purchases. And that selling could trigger a broader decline.

"Without fresh capital being added to growth mutual funds, I worry we could see declining valuations of existing companies wholly apart from the fundamentals. It's a real issue," Cramer said.

And to make matter that much worse, "I don't hear enough people fretting about it."

Call Cramer: 1-800-743-CNBC

Questions for Cramer?

Questions, comments, suggestions for the "Mad Money" website?