"There are many signs that this market is getting long in the tooth and a myriad of concerns could trigger a significantselloffover the summer. The two that seem to be going unnoticed by the market are the massive increase in merger and acquisition activity and what is happening in the IPO market. In short, the smart money is heading to the hills. Some would argue that these increases are a result of a robust and brightening economy and the unleashing of animal spirits after a few years of depressed activity due to the economic crisis. I would counter that some of the same arguments were made during the IPO and M&A booms of 1998 and 1999 as well as the private equity heyday of 2007. In both cases, the direct cause of the boom turned out to be more the excess liquidity that was available to go into risky assets."