It's widely acknowledged that buyout fever has to come to an end at some point, but few people in the press seem to be advocating this end coming soon. I guess I'm a contrarian on this issue -- I think there are clear signs that the private equity craze is wearing down. Well, a contrarian to everyone except the private equity firms' leaders.

Today, news that Apollo Management is hoping to go public through the "back door" hit the wires. This type of offering (called a 144A) allows Apollo to "sell shares of itself quickly while avoiding for several months the disclosure involved in a public offering," according to a New York Times piece on the story. This filing essentially allows Apollo to sell only to institutional and other "sophisticated investors," rather than any investor who can trade on the New York Stock Exchange. However, Apollo hopes to be trading on the New York Stock Exchange by the first quarter of next year, according to the Times.

For some reason, investors still want to buy into Blackstone Group (NYSE: BX), KKR's upcoming offering, and probably Apollo's future offering. I don't know how many times it needs to be said, but I'll say it again: these executives aren't selling to the public to share from their bounty -- they are selling out because they realize things can only get worse from here. Apollo isn't rushing to sell its company for no reason -- it believes bad times are coming.

In this week's Barron's [a paid service], there's an in-depth look at the mega IPO of the Blackstone Group (NYSE: BX). It's the most important IPO since the offering of Google (NASDAQ: GOOG), although investors shouldn't expect the same kind of returns.

While Google signaled a burst of growth in online advertising (which appears to be long-term), it looks like Blackstone is really signaling a top in the private equity space. Why?

Here are some bullet points:

Competition: KKR, Goldman Sachs (NYSE: GS), TPG, Apollo Management and others all have big war chests and are competing for deals. This drives up valuations -- making it more difficult to get strong returns. This is essentially what happened with venture capital during the internet boom.

Institutional Pushback: Institutions and hedge funds are pushing for higher prices on buyouts. An example is the Clear Channel (NYSE: CCU) deal.

Higher Interest Rates: Private equity has been blessed with dirt-cheap interest rates and this makes it easier to generate returns. But with interest rates climbing, things are getting more difficult.

Politics: Capitol Hill needs more tax revenues. So why not raise rates on private equity?

Yes, Blackstone has posted a stunning 22.6% average annual rate of return (adjusted for fees) since 1987. But, with all these ominous trends, will Blackstone continue the pace? And, is it worth paying 2 times the multiples of companies like Goldman Sachs and Morgan Stanley (NYSE: MS)?

Tom Taulli is the author of various books, including the Complete M&A Handbook and the EDGAR-Online Guide to Decoding Financial Statements.