Concerns about a 2008-style market meltdown may be buried under a sea of central bank liquidity, but what about the threat of a market “melt-up?”

Some strategists, like Edward Yardeni, are growing concerned about the prospect of that scenario.

Yardeni “remains a steadfast market bull” yet “finds himself increasingly preoccupied by a cloud on the horizon: the growing complacency of his fellow investors," according to The New York Times.

Related: “Secular” Bull Market Only In “Middle Innings”, Says Schwab's Sonders

Yardeni worries that not enough investors are concerned about bearish risks, and are pushing stock prices up more quickly and consistently. As a result, this could create a market “melt-up” fueled by excessive exuberance and setting the stage for a “nasty correction" -- maybe even a bear market.

As the Times points out, the Investors Intelligence Bull/Bear ratio jumped to 3.19 last week, up from 1.96 a few weeks earlier. (Ratios above 3.0 have often signaled the onset of a correction). The percentage of market bears fell to the lowest point since May 2011 at 16.5%.

Similarly, BofA Merrill chief investment strategist Michael Hartnett warned in a note last week that “it’s getting frothy man.”

More than $12.4 billion flowed into global equity funds for the week ending Oct. 30, with $4 billion of those being long-only funds. Hartnett said another $8 billion to $9 billion of inflows over the next two weeks could trigger a contrarian signal to sell.

He also noted the BofA Merrill Bull/Bear Index is on course to trigger a cautionary “risk-off signal” mid-November. It’s reading at a seven, on the bullish side of the scale, and a breach of eight would make him more negative in the short term.

Meanwhile, the Wall Street Journal reports investors are flocking to initial public offerings at the quickest pace since the financial crisis. October was the busiest month for U.S.-listed IPOs since 2007, and so far this year, 61% of companies selling U.S.-listed IPOs have lost money in the 12 months prior to their debuts. More broadly, comparisons are being made to the technology stock craze of the 1990s. We all know how well that turned out.

In the accompanying video, Aaron Task and I discuss the likelihood of a melt-up, and the comparisons to the tech craze.

Related: No Fed Taper But No Market Bubbles Either: Jefferies' Ward

Task makes a compelling point that on the way up since the lows of 2009, commentators have been warning that it’s a “sucker’s rally” driven by Fed policy. But Task disagrees.

“I do think you’re starting to see a switch in sentiment of people saying 'maybe there is something real here, maybe these markets are justified by what the economy is going to do,'” he says in the accompanying video, calling it a “transition phase to bullishness versus the euphoric phase.”