Defining periods of irrational exuberance can be difficult. However, one method to do so might simply be to look at the headlines. Here are this morning's:

• Crescent Real Estate Equities to be purchased by Morgan Stanley (NYSE: MS) Real Estate
• Payless ShoeSource (NYSE: PSS) to acquire Stride Rite (NYSE: SRR)
  
• Dow Jones & Co. (NYSE: DJ) controlling shareholders, the Bancroft family, meeting to review News Corp (NYSE: NWS) offer
• Sallie Mae making management changes for its take-private transaction
• Alcan Inc. (NYSE: AL) rejects Alcoa Inc.'s (NYSE: AA) $27 billion offer as inadequate
• MGM Mirage (NYSE: MGM) approach by Kirk Kerkorian's Tracinda Corp requires delicate strategy.

The headlines are not too different from the 1980's LBO boom when virtually every headline was associated with a hostile buyout of some sort. Are we approaching the end of the buyout binge? Most likely not. These periods can last for years.

This buyout boom has been fueled by a number of factors. The most important factor has been undervalued stocks, which, in many cases, still remains. In the post tech-telecom bubble of the 1990s, investors went into a cocoon while U.S. company management continued to grow earnings and increase returns on investment.

What will end this buyout boom? My bet is a massive bull market which pushes valuations off the radar screen of private equity.

In what looks like an effort to diversify away from its low-price and low-quality (although that has been improving of late) flagship brand, Payless ShoeSource Inc. (NYSE: PPS) is acquiring Stride Rite Corp. (NYSE: SRR), the leading retailer of footwear for children. I have fond memories of going to Stride Rite with my parents when I was younger to pick out new shoes, and a lot of other people have similar memories. Payless will pay $800 million in cash for the company.

The company will change its name to Collective Branding after the deal is consummated because it was the most boring name it could think of that wasn't already taken.

Shares of Stride Rite are up more than 30%, while Payless shares soared more than 10%, making this one of those rare deals that looks good for the acquired company's shareholders and the owners of the acquiring company.

Payless has been a strong performer over the past few years, as CEO Matt Rubell has focused on upping the quality of the company's products. This acquisition seems like a great way to continue on that path, and the company's balance sheet looks strong enough to handle it.