Buyout funds are not practicing similar restraint, they say. While it is not cataclysmic, buyout fund managers' fundraising universe is a mirror image of the venture capital world of 1999 and 2000, Mr. Lynch said.
"They are raising record-size funds, involved in bigger transactions for bigger multiples (higher prices) and taking on bigger risks," he said.
The risk-taking is evident in buyout club deals in which a group of buyout funds participate in a transaction. Buyout funds are exerting less control over the portfolio companies they are buying, which increases the risk, Mr. Lynch said.
"Our level of concern is up. We are more cautious about the buyout world today than we were in the past," he said.
What's more, there is a question whether buyout firms will be able to put all the committed capital to work.
"The shift in investment flows by certain hedge funds, BDCs (business development companies), others from public equities to private equity is a concern, because private equity is a small market by comparison — with a finite amount of great investment opportunities, " Mr. Sacks said.
A portion of the increase in real estate assets under management can be attributed to appreciation of real estate in general, said Michael McMenomy, global head of investor services at CB Richard Ellis Investors LLC, Los Angeles. (CB Richard Ellis Investors reported $7.26 billion in domestic equity real estate under internal management.)
"That is one element that has fueled assets under management," he said.
Another factor was an increase in capital flows into real estate, reflecting investor demand for the asset class, Mr. McMenomy said.